Several times a day internal LAN routing becomes intermittent for random IPs

[hsfetterman]

I've been run OPNsense since January 2026 and have been having lan side routing issues ever since the initial installation, persisting through to the latest 26.7 update. After several hours of uptime the lan side network begins having issues reaching several random internal IP addresses, ping and fetch will fail.  I can temporarily repair the routing by issuing, configctl interface reconfigure lan, at a command prompt, or many times by just toggling the lan interface. This routing issue has been happening 1-3 times a day. My network consists of many IP security cameras of various brands and this becomes noticeable on an Android app called IP CamViewer, which aggregates all of the camera streams into a matrix of views. These streams rely heavily on UDP. The 24 camera streams will typically load in about 20 seconds, but when this issue is happening, many streams fail to load or take 30 seconds to load. I've also noticed that my WiFI has trouble connecting

I've tried all the suggestions I've found online such as turning off the NIC's power management features in the BIOS, changing some of OPNsense settings, and locking the NIC to 1Gb/s. I know it is not an issue on my internal lan hardware because it will run for months when using another router. To me it seems like some internal routing table is getting corrupted and issuing the reconfigure resets its state.
 
I'd welcome suggestions on how to track down what is causing this instability. What logfiles, internal databases or tables should I monitor?  For those that know the OPNsense internals, what is getting reset when I issue the reconfigure or toggle the lan interface? The issue occurs so often that I wrote a script, that runs under cron, to ping and fetch from about 10 internal IPs, and automatically issue a reconfigure when a few fail.

I'm running on an ASRock Industrial NUC BOX-255H with an Intel Core Ultra 7 255H, 32G of RAM and a 400 GB SSD. The only add-on package installed is WireGuard. The lan side NIC, igc0 is reported as:  

 pciconf -lv | grep -B3 -A2 igc0
    device     = 'XG3 NVMe SSD Controller'
    class      = mass storage
    subclass   = NVM
igc0@pci0:115:0:0:      class=0x020000 rev=0x04 hdr=0x00 vendor=0x8086 device=0x125b subvendor=0x1849 subdevice=0x125b
    vendor     = 'Intel Corporation'
    device     = 'Ethernet Controller I226-LM'

[cookiemonster]

Problem here is that we can't guess your internal setup. You talk about routing but all "internal" traffic i.e. devices talking to each other in your "LAN", they don't go through your OPN router. They talk via a switch that you will have downstream of OPN and plugged into that LAN port.
That said, it could be routing if you have more than one network segment and traffic has to go through your OPN, but this is what we can't guess. You must give us all the details.
Finally if resetting that interface seems to make a difference, that suggests the router is involved somehow. Again tell us the setup.
And hello to  you too.

[nero355]

I've been run OPNsense since January 2026 and have been having lan side routing issues ever since the initial installation, persisting through to the latest 26.7 update.

After several hours of uptime the lan side network begins having issues reaching several random internal IP addresses, ping and fetch will fail.

This routing issue has been happening 1-3 times a day.

How does that traffic flow : Within the subnet of between two different subnets ?

My network consists of many IP security cameras of various brands and this becomes noticeable on an Android app called IP CamViewer, which aggregates all of the camera streams into a matrix of views.
These streams rely heavily on UDP.

The 24 camera streams will typically load in about 20 seconds, but when this issue is happening, many streams fail to load or take 30 seconds to load.

I've also noticed that my WiFI has trouble connecting

That part sounds like Multicast Traffic flooding your network ?!

IGMP Snooping can fix that if your Switch(es) support it.

I know it is not an issue on my internal lan hardware because it will run for months when using another router.

And which Router is that ?

Does it happen to be from your ISP and includes a configuration for IPTV ?
If so, then it probably does the above mentioned IGMP Snooping for you ;)

[pfry]

[...]I'd welcome suggestions on how to track down what is causing this instability. What logfiles, internal databases or tables should I monitor?[...]

The fit is imperfect, but I'd look at ARP. Assuming the sysctl "net.link.ether.inet.log_arp_movements" is set (the default), ARP movement will show up in "System: Log Files: General" (IIRC). I'd also manually check ARP via "Interfaces: Diagnostics: ARP Table" (value, not just presence).