ISP Upload gets very slow

[Matrix3000k]

I am using a barebone hardware that I ordered from amazon and running the latest version of open sense on it. The device/router has 4 10GB SPF slots and 5 2.5GB ports. When I plug into the 2.5GB ports my download and upload speeds are fine. The moment I plug an multi gig sfp+ and plug my pc into that, my download speed remains just fine but my upload speed goes from 50MB per second down to 4 or 5 MB per second. I have tried multipule sfp's with the same result. I am thinking the issue has to be some sort of configuration in opensens that is slowing down my upload speed. Has anyone run into this issue or know how to fix it? Im not a noob at this but im not an expert either.

[CornyBee31]

I have the same issue but haven't found a solution as yet :(

[MagikMark]

We have a similar issue.  In my case, if a client uses a VPN app, upload speed drops

[amitsax]

Similar issue - using opnsense on proxmox. ISP speed ~300 symmetrical. upload getting 291, download hitting 4.

[meyergru]

@amitsax: And surely enough, you have read both this, which would have guided you to look at the tutorial section, and then you found this and followed all recommendations about network "hardware" in that?

And with all that knowledge in mind, you might have noticed that most probably, your situation differs greatly from the other ones, just because OpnSense does not even control the adapter (unless you have chosen to use pass-through, which of course may be a problem in itself, but you did not share that vital information, yet), so you should start a new thread, giving all neccessary information instead of reviving an old one that does not fit your specific situation.

Sorry to sound rude, but sometimes, it just saves time for both you and me...

[amitsax]

@amitsax: ...so you should start a new thread, giving all neccessary information instead of reviving an old one that does not fit your specific situation.

Sorry to sound rude, but sometimes, it just saves time for both you and me...

I think, recommendation to start a new thread, is on-point - I just checked for latest updated thread to pile on with my slow upload report.
My setup is not a new setup, I have been on this setup for a while now. Just recently (in last couple of updates) I started noticing issues, in day-to-day operations. I have had the considerations of opnsense under proxmox taken care of, I will recheck, if any new recommendation have surfaced.
EDIT 1: After checking for different changes, and settings - and coming empty handed, for the time being I have dusted up my back-up router, that brought me back to 300 up and down. Given that during the last couple of weeks (May,2025) both proxmox and opnsense dropped updates, something seems to have gone wrong with MY setup. Will open new thread, once I have more time to check on it.
EDIT 2: Tried again this weekend. It seems after recent proxmox kernel update things are back to normal. I didn't have to do any other tweak.