Network stops working when PCIe card plugged into PCIe slot1?

[gar13]

Hello,

I am unable to use the PCIe slot 1 in my server. It is a intel i7-11700k on a MSI z590 gaming plus motherboard with 64g RAM. When I plug any PCIe card into slot 1, the network is unresponsive and I am unable to connect to the server. There doesn't seem to be anything different on the server console and it states it is available to configure on the correct IP address. To rule out a hardware issue, I installed windows 10 on a separate drive bare metal with this server. With Windows 10, both the network and the card plugged into Slot 1 work perfectly.

With this motherboard, the PCIe slot 2 is shared with the sata controller for some of the m.2 slots. I realize that PCIe slot 2 should not work with my config. Slot 1 however should be connected directly to the CPU (not through the chipset), so I am at a loss to explain why networking cuts out. Some hardware conflict in Proxmox is my only guess.
(I've attached the block diagram for this motherboard chipset) I'm really stuck on diagnosing the cause of the issue as I am unable to connect to the configuration screen to diagnose any issue. Any help would be greatly appreciated.

 

[leesteken]

The name of the network device depends on the PCI ID, and the PCI ID depends on the number of devices (with a lower ID). Every time a PCI(e) device is added or removed, the name of the network devices changes (one of the numbers in the name changes by one).
Login to the Proxmox host console (using a physical keyboard and display), check the output of ip a and change the network configuration accordingly using nano /etc/network/interfaces.
Lots of people run into this and there are various threads on this topic, so my apologies for being a bit terse. This is the most recent one.

 

[gar13]

Thank you, I understand, please don't apologize. You have been extremely helpful. Honestly, I should have thought of checking interface config, but went down a different rabbit hole...again thanks for the reply.