New install not recognizing second NIC

[Raptor2213]

I've set up a new install using two 2.5g NICs of the same brand/model, and am having issues with setting them up. Both NICs were installed when the machine was started up, but only one was connected during the install.

The GUI is only showing 1 NIC:


It looks like the system is seeing the second link, but calling both NICs eno1

root@Aurora:~# lspci -k | sed -n '/Ethernet/,/driver in use/p'
06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8125 2.5GbE Controller
        Subsystem: Realtek Semiconductor Co., Ltd. RTL8125 2.5GbE Controller
        Kernel driver in use: r8169
07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8125 2.5GbE Controller
        DeviceName: RTL8111EPV
        Subsystem: Realtek Semiconductor Co., Ltd. RTL8125 2.5GbE Controller
        Kernel driver in use: r8169
root@Aurora:~# dmesg | grep r8169
[    1.433631] r8169 0000:06:00.0: enabling device (0000 -> 0003)
[    1.443306] r8169 0000:06:00.0 eth0: RTL8125A, 78:2d:7e:1e:a0:bf, XID 609, IRQ 57
[    1.443310] r8169 0000:06:00.0 eth0: jumbo features [frames: 9194 bytes, tx checksumming: ko]
[    1.443338] r8169 0000:07:00.0: enabling device (0000 -> 0003)
[    1.450855] r8169 0000:07:00.0 eth1: RTL8125A, 78:2d:7e:1e:93:ca, XID 609, IRQ 74
[    1.450859] r8169 0000:07:00.0 eth1: jumbo features [frames: 9194 bytes, tx checksumming: ko]
[    1.776265] r8169 0000:06:00.0 enp6s0: renamed from eth0
[    1.800267] r8169 0000:07:00.0 eno1: renamed from eth1
[    6.014196] r8169 0000:07:00.0 eno1: entered allmulticast mode
[    6.014251] r8169 0000:07:00.0 eno1: entered promiscuous mode
[    6.038256] RTL8226 2.5Gbps PHY r8169-0-700:00: attached PHY driver (mii_bus:phy_addr=r8169-0-700:00, irq=MAC)
[    6.205687] r8169 0000:07:00.0 eno1: Link is Down
[    9.720325] r8169 0000:07:00.0 eno1: Link is Up - 2.5Gbps/Full - flow control rx/tx

How can I reconfigure it to use the second NIC?

 

[sw-omit]

I'm half-suspecting that that enp6s0 actually IS your second network-card (or perhaps that the second one is the eno0 and the first has been changed to the enp6s0)
One way to check would be to check the mac-address on the card itself, which one is which. They seem to be 78:2d:7e:1e:a0:bf and 78:2d:7e:1e:93:ca from the log.
Alternatively, you could assign your own name to each device based on that same mac-addres with .link files [1] (Do be sure to start their name with en and not conflict with exisiting namings, so for example end1p1 (for Device 1 Port 1) and end2p1 (for Device/Card 2, Port 1)

[1] https://pve.proxmox.com/pve-docs/pve-admin-guide.html#network_override_device_names

 

[Raptor2213]

Unsure how to do any of that (aside from physically looking at the MAC address). Also, this is in a server, so the card isn't exactly easily accessible.

 

[sw-omit]

Servers I know are sometimes even easier to access things like the stickers of the network-cards then on PC's, but that's beside the point.

Both the mac-addresses I mentioned come back to manufacturer TRENDnet, but since there is such a large / strange gap between the mac's, I would doubt it be something on the same card, so that is why I think they are the two different cards.

If you can't get physical access to your server, one way you could try, if you have the option to remotely disable a port on the switch the server is connected to, disable one of the ports on the switch, check if the server is reachable on the still active port, then swap both the config and the disabled port to the different one, and see if it is then still/again reachable.

So config on port eno1, disable port 1 on switch:
Active? Good, then port 2 on the switch is eno1, now disable port 2 and activate port 1, and connection should stop (to verify)
Not reachable? Enable port 1 on the switch and disable port 2, now active? Port 1 is eno1

Switch config to port enp6s0, disable the port you now know is eno1, and enable the other one:
Can you now reach it? than that port is enp6s0, again switch the active port on the switch to verify your setup.
Can you not? Check config again, else it really might only be seeing one of the cards.

 

[Raptor2213]

There's no link lights on the inactive NIC, so I'm confident that it won't fail-over if I disconnect the working port, so I don't believe that is possible. I also don't know any of the steps needed to perform anything but the physical portions of that.