I have a Proxmox 8.1.x box build on an Asrock Rack E3C246D4U motherboard. The board comes with two Intel i210 1g nics, one of which connects to the LAN and the other is idle,. When I built it, I added a Mellanox Connect X 3 10g SFP+ card, which has a direct connection to an identical card in my TrueNAS box. All has worked well for several years.
Recently, I bought a 2.5g switch and several Wirenest 2.5g nics (which appear to be i225-v rev.1). My plan is to use the 2.5g nics for LAN traffic and forgo using the slower onboard 1g nics on both boxes. I added one of the new cards to the FreeNAS box and all is well/working as expected; however, when I added the second 2.5g nic to the Proxmox box, the Mellanox card vanished. Running lspci -v (or dmesg | grep eth OR grep net) does not show it or its driver. Pop the card out and all is well again. I’ve tried swapping the two 2.5g nics and everything continues to work fine on trueNAS and not working on Proxmox—which makes me think this is a software, not a hardware problem.
Any thoughts on how to fix this?