Well, you could say I should have known better - yet, I tried:
Recently, I saw an article about the new RealTek RTL8127 NIC. On paper, it looks fine: 10/5/2.5/1 Gbps, low power draw and PCIe 4.0 x1 interface, which makes it easy to fit into any mainboard - or so it seems.
Main main reason to use it were the shortcomings of other high speed RJ45 adapters, like the X550-T1. That one:
- uses much more power
- needs a PCIe 3.0 x4 slot
- cannot handle autonegotiation on some OSes
Because I have not-so-good CAT.5E cabling, I like to use 5 Gbps, but with newer Windows drivers, you cannot even fix speeds at NBase-T (5 or 2.5 Gobs), so you are mostly stuck with 1 or 10 Gbps only. Linux is a prominent example where the driver allows intermediate speeds, see this for details (https://forum.opnsense.org/index.php?topic=48933.0).
I already had a Realtek RTL8126, which can do 5 Gbps at most, but that one had a quirk: On cold boots, it was sometimes not detected at all. Only a power-cycle would help. The internet is full of discussions about that. So, I went for it and bought the RTL8127...
...only to find that it had the same quirk.
But now comes the hard part: My Windows 11 installation has gone awry in the last few weeks. Basically, I could not start Steam and Ollama any more. Nothing I did could repair it.
On I went with a new installation from scratch and restoration of my user files afterwards. Then, I had to install every application again.
System worked fine for ~24 hours, then I noticed strange things happening: My desktop icons flashed ever 0.5 seconds and I could no longer set the default browser. No repairs worked here, either.
Since I still had the profile backup, I decided to repeat the whole process. While I was doing that, I tried to relocate the RTL8127 into another PCIe slot. This time, the restoration of my user profile showed 3 CRC errors. I was quite sure there were no problems on the source.
So, the plot thickened: Obviously, in my X570 board, the PCIe 4.0 slots attached to the chipset have problems. The X570 chipset was the first to use PCIe 4.0, so the implementation may be flaky. At the time, nobody would have noticed, because most PCIe cards only supported PCIe 3.0 anyway.
Now, the problem manifests in two ways:
1. The NICs may sometimes go undetected during cold start PCIe training.
2. The data that is transferred to the mainboard can get corrupted. This became very obvious when I installed some 500 GByte of software and data over the network.
I am quite sure that this caused all the other problems, too.
TL;DR: The newer Realtek chips RTL8126 and RTL8127 do not run reliably on older hardware that "supports" PCIe 4.0.
Of course, this is independent of OS. You might also say that is not Realtek's fault, but at least, it does not happen with the Intel X550-T1, which only uses PCIe 3.0. BTW: It only works with either PCIe x4 or x1, so my x2 slot was a waste.
I'd punish you by sending you all of my old Aquantia and Tehuti hardware, but the joke wouldn't be worth the ridiculous international shipping.
It might not be worth it, but you should be able to set the PCI-e version in the BIOS. (I can find it easily, but only if I'm looking at it.)
Nope. In that BIOS, I can only set the PCIe speed for the CPU lanes and the chipset lanes separately, not per slot. And since the CPU lanes are solely used for the graphics card, I can only set all of the chipset lanes together, crippling my NVME drives.
Apart from that, I suspect that these problems are with the NICs - when you skim through the reports, you will find newer affected chipsets like X870. I doubt that my Asrock board is the culprit here and maybe even going back to PCIe 3.0 would not cut it.
After having seen these corruption problems and all my time invested chasing ghosts, I won't place any more bets on these things, either.
P.S.: I have an Aquantia here, as well. Never worked right. I even had a conversation with their CEO on that back in the day...
Quote from: meyergru on February 11, 2026, 10:10:11 PMIn my X570 board, the PCIe 4.0 slots attached to the chipset have problems.
The X570 chipset was the first to use PCIe 4.0, so the implementation may be flaky.
At the time, nobody would have noticed, because most PCIe cards only supported PCIe 3.0 anyway.
IIRC there were plenty of websites that wrote a lot about that issue when the AMD Chipset was released ?!
IMHO a great part of the issues comes from the fact that ASMedia a.k.a. ASUS was involved in the design and manufacturing process of the Chipset at the time.
Do you have any Intel based systems to test with ?
I am pretty much done with buying AMD for about 15 years or so now...
No, but the reports on the internet were all over the place and some were Intel boards, too, like this:
https://www.reddit.com/r/Fedora/comments/1p1syhw/realtek_rtl8127_dropping_out/
Quote from: meyergru on February 12, 2026, 12:12:05 AMsome were Intel boards, too, like this:
https://www.reddit.com/r/Fedora/comments/1p1syhw/realtek_rtl8127_dropping_out/
That's another AMD Chipset ?!
P.S. :Even tho I am not a big Reddit fan I know their "forum" is a lot nicer to read when using old.reddit.com and that way it's also not so extremely white ;)
Correct. But problems with Intel chipset have been reported earlier:
https://www.hwcooling.net/en/realtek-rtl8126-suffers-from-instability-no-5-0gb-s-ethernet-this-year/
It is also clear that the cards have a problem with ASPM:
https://forums.servethehome.com/index.php?threads/realtek-10-gbe-usb-adapters-might-be-on-the-way.47683/post-489414
Wanna buy my adapters?
Quote from: meyergru on February 11, 2026, 11:16:30 PMI have an Aquantia here, as well. Never worked right.
No problem here with the realtek or aquantia, although I am only using them with PCIe3 and as direct connections to each other, in Windows.
Quote from: meyergru on February 12, 2026, 08:00:04 PMWanna buy my adapters?
NOPE.AVI ^_^
Already got too much stuff hanging around here unused... LOL!
Good thing you posted this, I had been considering one (specifically the SFP+ variant on AliExpress) to replace a SolarFlare SFC9020 SFP+ NIC in my desktop. What do we think of Aquantia AQC113 as an alternative?
I had an older Acquantia when their 10 Gbps specimens came out, it never worked right. AFAIK, driver support under FreeBSD lacks, too. I would take the Intel X550.
Yeah, I had been hoping for something PCIe 4.0 that I could use in a 1x slot on my B550 with my Linux desktop. Guess I'll just stick with the SolarFlare in a 4x slot for now.
Actually, I had quite a zoo of these adapters over time, which do not help my situation at all.
This is because the cabling in my flat is so bad that I need 5 Gbps NBase-T to work reliably.
I actually got two Intel adapters when they came out at half price - AFAIR, they were $800 each at regular price. Those were even full cards.
Then, I used X540. but those can do only 1/10 Gbps.
After that came a Buffalo LGY-PCI-MG, which is an AQC107. This never worked quite right. I also cannot load either newer Aqantia driver nor update the firmware, because Buffalo used an exotic PCI ID. It is a catch-22.
I also had an older ASUS XG-C100C with the AQC107.
Now I have a X550-T1, which I bought a few years ago, only to learn now that there are several variants (AT, AT2, BT2). I was able to flash to the newest firmware, but that does not help, because my specimen, like many other china ones, is a revision 1, which physically cannot do N-Base-T. With 10 Gbps, these things get so hot that they start to drop packets when the are under load and they take a boatload of power (~8 Watts). For NBase-T, you need both a revision 2 and current firmware.
My experiments with the newer Realteks RTL8126 and RTL8127 are now documented above. Maybe it would be wise to get an RTL8127AT, which can use more than one PCIe lane, but I think that in a PCIe 4.0 x4 slot, they will prefer PCIe 4.0 x1 over PCIe 3.0 x2 (they can do both) and cause the same problems.
And just now I have ordered a new Asus XG-C100C V3, which uses the AQC113C and finally should do the trick... mind you, that is only for Windows, not for FreeBSD, as it appears (https://forum.opnsense.org/index.php?topic=48120).
Any BIOS updates for the X570 board by chance? Sometimes they don't explicitly document fixes but a new AGESA or something might fix some initialization quirks.
I am already on the second but last one and considering the risk for my system and the restoration time I would be looking at, I am not willing to take that risk any more.
Quote from: meyergru on February 15, 2026, 10:13:02 AMthey will prefer PCIe 4.0 x1 over PCIe 3.0 x2 (they can do both)
Don't think so, I bet the x4-card will only do PCIe3. But if you had no luck till now, it will not change with these.
I've seen the 8127ATF SFP+ NICs and I wonder if they work any better than the 4.0 1x BaseT cards. I've also noticed they're all 4x, so they're presumably PCIe 3.0 only. If they are, putting them in a 1x slot wouldn't get a full 10 gigabits, but it would still be 7.5 gigabits which ehhh... close enough.
I think that is a misconception. Realtek advertises those AT variants as being either PCIe 4.0 x1 or PCIe 3.0 x2, but that is only to show its capability to support the full needed bandwitdh with PCIe 3.0 mainboards (provided that they have at least 2 free lanes).
Matter-of-fact, the cards will train at the highest speed they can find. That is just how PCIe works.
So, if you put them into a PCIe 4.0-capable system, they will use PCIe 4.0 x1, regardless. he only only you have on a PCIe 4.0-capable system is to limit the slot to PCIe 3.0 only. Givingg the card more lanes is not gonna cut it.
As it turns out, these Realtek adapters are on the edge of the PCIe 4.0 specification and the X570 chipset is known to be finicky as well. You may have better luck with other mainboard chipsets.
Well,
maybe already obvious but why not to switch OS on the PC? Is there a reason you need to run Windows instead of Linux?
I know its OS independent, but if there is solution to be found or stability to be gained its far more prompt to be on Linux distributions than on Windows these days.
Regards,
S.
I use apps and games that are only available on Windows. Besides, this is a hardware issue.
True to that,
What I can tell you from point of Linux and Realtek.
I have a X870 tomahawk Mobo, its a 5G realtek NIC basically its the RTL8126 and I run it on r8126 driver.
Device-2: Realtek RTL8126 5GbE vendor: Micro-Star MSI driver: r8126
v: 10.016.00 modules: r8169 pcie: gen: 3 speed: 8 GT/s lanes: 1 port: e000
bus-ID: 0a:00.0 chip-ID: 10ec:8126 class-ID: 0200
IF: enp10s0 state: up speed: 1000 Mbps duplex: full mac: <filter>
Info: services: NetworkManager,systemd-timesyncd
I run it only at 1G, reason is I do not have currently a better switch. But at least on this speed its rock solid, didn't had yet any issues.
Regards,
S.
Interesting, actually, the RTL8126 is a PCIe 3.0 card - and it runs like that on your board:
v: 10.016.00 modules: r8169 pcie: gen: 3 speed: 8 GT/s lanes: 1 port: e000
So it seems the instability is with PCIe 3.0 as well with my X570 board.
Makes me wonder how it would fare on my B550 board on a chipset 3.0 slot.
Yes,
This NIC is embed on the MOBO, and runs at a single PCIe 3.0 lane, as its enough for the capacity. Also I didn't set the gen or speed on the PCIe, this is the only thing I didnt play with on the MOBO. It was set by the system itself/MOBO. For OS if you are interested I run GarudaOS, which is an Arch based distro. Primary usecase of my beefed PC is gaming.
I would suggest to search for BIOS updates. As these usually improve the compatibility and functionality.
The X570 MOBOs were/are not a low end MOBOs, so I would assume they should have proper BIOS support and feature advancement thru the years.
Regards,
S.
See #14. I have contacted Asrock tech support about this, but for what I am reading about both B550 and X570, PCIe problems are reported all over the internet. Those chipsets are themselves problematic, as it seems.
Maybe it is time for a better system - this would involve buying DDR5, though. So, at current prices, I will make do with the new NIC first.
Quote from: meyergru on February 16, 2026, 12:43:26 PMthis would involve buying DDR5, though. So, at current prices, I will make do with the new NIC first.
There are hopeful signs already that the memory shortage might resolve itself sooner rather than later. ;-)
If nothing else, Chinese makers (CXMT) are ramping up...
As for AM4, they did have early teething issues with PCIe 4.0. I recall lots of gamers then were complaining about USB interference and mouse stutters that AMD only resolved after several AGESA iterations. But, I thought that the issues were mostly in the rear view mirror now. Maybe not entirely.
Quote from: meyergru on February 16, 2026, 12:43:26 PMSee #14. I have contacted Asrock tech support about this, but for what I am reading about both B550 and X570, PCIe problems are reported all over the internet. Those chipsets are themselves problematic, as it seems.
Maybe it is time for a better system - this would involve buying DDR5, though. So, at current prices, I will make do with the new NIC first.
Yea, I understand you have some good reasons not to do it but that's the only way to move with this.
Also I am 99% sure their support will give you just half-based answer and tell you to upgrade BIOS.
You are generally right the X570 the first that came out had funky problems.
Same was with 1st gen of DDR5 MOBOs X670 & B650 that was just painful. But for a fact I know with time and BIOS updates a lot of problems of the x670 & B650 were solved, but not all. The x870 is just a rebranded B650E. But a lot of nonsense was fixed from previous generations. I have this MOBO since release and I was kinda 1st adopter of it on Linux, here and there some funny business, but MSI pushed BIOS updates very fast. Now its rock solid, and I have even the mems OCed at 8000Mhz.
I would wait with upgrading to a new system. The prices of all components are like a water slide.
Cheapest or best option currently usually is to buy a prebuild system and gut it into a custom one. (depends on country, tho DE is a bigger marked than CZ)
Regards,
S.
Quote from: Bob.Dig on February 12, 2026, 09:45:13 PMQuote from: meyergru on February 11, 2026, 11:16:30 PMI have an Aquantia here, as well. Never worked right.
No problem here with the realtek or aquantia, although I am only using them with PCIe3 and as direct connections to each other, in Windows.
For completeness, I have four NICs of the RTL8126, two PCIe and two m.2, all work/ed fine in conjunction with intel X550 and AQC107 and also with this switch: Zyxel XGS1250 Desktop Gigabit Smart Switch. I don't think that any problem would be chipset-related.
If you cross-flashed a marvel-firmware on an asus-card, there is a possibility for driver problems with windows, which is resolvable.
Yes, I tried. But it actually is a catch-22: Without the driver (which does not load because of the PCI ID) you cannot use the flash tool. And you need the flash tool to change the PCI ID. The only way to make it work it to use the standalone UEFI flat tool aqflash.efi.
Aquantia themselves once had these tools, but they discontinued it. The only way to get them is from Asus, because they had these chips on some motherboards. But their site was down over the weekend.
After all, the AQC107 uses much more power than the newer AQC113C and I will get one this week...
Quote from: Seimus on February 16, 2026, 12:06:39 PMThe X570 MOBOs were/are not a low end MOBOs
Depends how you look at it...
Somewhere around the time of the X470/X570 motherboards their prices went up, up and up again to levels that would make you think they are High End models, but none of them come even close to what was previously offered such as something like the beautiful AsRock Z87/Z97 Extreme11 for pretty much the same price : Somewhere around € 300 IIRC :)
And that was just a Mainstream model and not even a HEDT model like it's big sister the AsRock X79 Extreme11 that was somewhere around € 500 when I bought it which is/was an actual High End motherboard because of the fact it's in the HEDT category instead of the Mainstream category ;)
(I have always bought HEDT components in the past before everything went out of control starting with the Intel 7000 Series HEDT CPU's because it doesn't give you any of the annoying PCIe lanes limitations like the Mainstream models still do up to this day...)Quote from: Seimus on February 16, 2026, 01:08:47 PMYou are generally right the X570 the first that came out had funky proble ms.
Same was with 1st gen of DDR5 MOBOs X670 & B650 that was just painful. But for a fact I know with time and BIOS updates a lot of problems of the x670 & B650 were solved, but not all. The x870 is just a rebranded B650E. But a lot of nonsense was fixed from previous generations. I have this MOBO since release and I was kinda 1st adopter of it on Linux, here and there some funny business, but MSI pushed BIOS updates very fast. Now its rock solid, and I have even the mems OCed at 8000Mhz.
The above is why the AMD Athlon 64 X2 4400+ was my last AMD CPU and the AMD Radeon 290X 8 GB my last AMD GPU : Too much
"Ohh... yeah... that did not work out as we expected/wanted it to... Oops!" nonsense all the time !! :(
QuoteI would wait with upgrading to a new system. The prices of all components are like a water slide.
Cheapest or best option currently usually is to buy a prebuild system and gut it into a custom one. (depends on country, tho DE is a bigger marked than CZ)
^^ That + combine it with looking for some nice discounted offer too!
Especially Gaming Laptops and PCs can be very interesting that way :)
Another option is to gather multiple components during a longer period and collect them from multiple discounted offers, but that involves taking a bigger risk and you never now what you are going to get, however if you want to save a lot of money and avoid certain prebuild brands it could be your best option...
Quote from: nero355 on February 16, 2026, 04:37:24 PMThe above is why the AMD Athlon 64 X2 4400+ was my last AMD CPU and the AMD Radeon 290X 8 GB my last AMD GPU : Too much "Ohh... yeah... that did not work out as we expected/wanted it to... Oops!" nonsense all the time !! :(
I am running a full AMD system since last year where I did upgrade my old AM4 platform. The only thing I kept are the NVMEs, PSU and chassis + fans;
9800X3D
9070XT Merc
Tomahawk X870
G.Skill Trident Z5 RGB 32GB (2x 16GB) 7800MHz
Got all of these components at or under MSRP. I am running as well since 3y+ Linux, this upgrade was done in mind of Linux. And personally I do not have any problems on that system running Garuda under the hood. In respect of stability and feature system HW/OS works perfectly fine without problems.
Intel based system have their quirks too.
Regards,
S.
Quote from: Seimus on February 16, 2026, 04:57:57 PMI am running a full AMD system since last year
And personally I do not have any problems on that system running Garuda under the hood. In respect of stability and feature system HW/OS works perfectly fine without problems.
I know there are plenty of systems out there without any issues, but it also depends on your needs for a part and in that regard I am really done with AMD hardware :)
QuoteIntel based system have their quirks too.
Ofcourse, but they tend to
'Just work!' a lot more compared to AMD stuff in my experience.
It's a shame tho, because I kind of fell in love with the Ryzen 2200G when it came on the market : A small powerfull cheap APU that could do a lot of things for a lot of people in something like the AsRock A300/X300 models or some kind of "AMD NUC" concept ^_^
Quote from: nero355 on February 16, 2026, 05:09:50 PMOfcourse, but they tend to 'Just work!' a lot more compared to AMD stuff in my experience.
I sadly do not agree with this. I have very bad experience with Intel and DDR5, and that doesn't apply only for PCs but as well Server systems.
Regards,
S.
Quote from: Seimus on February 16, 2026, 05:17:51 PMI have very bad experience with Intel and DDR5, and that doesn't apply only for PCs
Is those were ASUS mainboaards then I am not surprised to be honest.
Also some of the Intel N100 (and others) "NUC" like models can be picky about RAM.
Quotethat but as well Server systems.
In the Server/Workstation world that's considered normal and I have epxerienced it myself with many HPE models from the E5-2650v1/v2/v3 era in the past :)
As of about a year ago, the Marvell AQ drivers were not available, whether I wanted to use it or not, I had to go with Truenas Scale on a mini-NAS I was building. Marvell AQ drivers are available in Linux (for as good as they are, have a new problem with Truenas 25.10.x).
Intel still rules the roost and thankfully the x710 are (were) coming down in price.
And I sure hope RAM and SSD prices come back down, not going to waste time buying when they get back into the comfortable range, I could use some 2-4TB nvme drives and $50 per TB sure is better than $100+ right now.
The X710-T2 is still at ~235€. I think that is a little steep when a full mainboard costs less. The XG-C100C can be had for 63€ shipped.
Just a quick reminder for everyone that Seimus has a working Aquantia driver which is likely to land in 26.1.3
https://forum.opnsense.org/index.php?topic=48120.0
Quote from: meyergru on February 16, 2026, 11:07:18 PMThe X710-T2 is still at ~235€.
You could check if this webshop delivers to Germany : Intel X550 RJ45 for € 150 @ Uptimed.nl (https://www.uptimed.nl/producten/netwerkkaarten/10g-server-dual-rj45-netwerkkaart-intel-x550-chipset)
/EDIT :Quote from: meyergru on February 17, 2026, 02:52:47 PMRead #12 on why the "cheap X550" adapters are bad: They use the revision 1 of the chipset, which cannot do NBase-T. I know that the link you are pointing to says otherwise, but I am 99% sure that they do not know the difference or do not know that their X550 are in fact based on old batches or refurbished cards. From the looks of it, I would guess this is a chinese clone.
Also, X550 take 8 Watts for one port, up to 11 Watts for two.
d0h!Now that you mention it : I think I have read that before here on the forum!
My bad! ;)
Read #12 on why the "cheap X550" adapters are bad: They use the revision 1 of the chipset, which cannot do NBase-T. I know that the link you are pointing to says otherwise, but I am 99% sure that they do not know the difference or do not know that their X550 are in fact based on old batches or refurbished cards. From the looks of it, I would guess this is a chinese clone.
I fell for the same mistake. Like many people, I looked up the specs and never noticed that NBase-T support depends on firmware and chip revision with these adapters.
Also, X550 take 8 Watts for one port, up to 11 Watts for two. The AQC113C ist at ~3 Watts for one port. Also, it costs 63€ only and can work with PCIe 4.0 x1, where the X550 needs more more PCIe 3.0 lanes.
I got the Asus XG-C100C V3 now and it works just fine (even with 10 Gbps). The only critical thing is that I had to disable EEE, which is a known problem for the AQC113C adapters. Even with 10 Gbps and sustained transfers, the heat spreader does not get too hot and retry rates are very low.
Mind you: this is in a Windows 11 PC - as already discussed, driver support for OpnSense is still in early stages (https://forum.opnsense.org/index.php?topic=48120.0).
Glad to hear you were able to find a suitable working replacement.
The temps are interesting, but the Asus card has a beefy heatsink on them. In a mini PC it will be interesting tho.
I have the Q11032H6, there the Aqua NIcs are part of the chassis heatsink with a thermal pad between.
Regards,
S.
I'm buying my lab x710 used, a quad port was only around $125 a few months ago, now they are probably on par with weight in gold. And so far I've only used them at 10g and 1g speeds, so not sure about nbase. Mine are also the Supermicro variant, they always seem to draw less power and I know I can get drivers and firmware if needed.
the dual port x710 were going for around $40 on ebay back then, I almost went that direction but decided I would get a couple quad port. I do want to upgrade the rest of my lab with dual port, I have x520-da2 installed into PCIe 3.0 slots, may be dragging the computers down a little. Most lab upgrades are on hold due to rising prices and lack of time to work in it.
Good news on the AQ driver coming soon, that should open up a few options.