I have a dual wan setup at home and I would like to configure some containers to go on the secondary WAN.

In order to do this I wanted to just connect the second ethernet port to the motherboard and from there set a forwarding rule in the router.

I'm stuck at the first step, after connecting the ethernet cable to the motherboard i can't manage to have it show up in Network Settings.

Only the "Interface eht0" tab appears and with Bridging enabled only eth0 is selectable.

I've tried rebooting the NAS with no success.

Both ethernet devices show up in the System Devices List like this:

IOMMU group 26: [10ec:8125] 06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8125 2.5GbE Controller

IOMMU group 27: [8086:1539] 07:00.0 Ethernet controller: Intel Corporation I211 Gigabit Network Connection (rev 03)

eth0 and eth1 show up in "Interface Rules" but with the same MAC adress and trying to edit anything gets me an "MAC address mismatch Rules contain duplicate MAC address assignments" error.

The motherboard is a "Asus ROG Strix X570-E Gaming" with a "AMD Ryzen 9 5900X"

What can I try to do?

Thanks

tower-diagnostics-20251031-1819.zip

Both NIMCS do have the same MAC address; that is a big no-no. It should be unique; there may be a BIOS/firmware update to change it:

Oct 30 18:05:53 Tower kernel: eth0: 0xffffc90000840000, f0:2f:74:cc:72:94, IRQ 24

Oct 30 18:04:22 Tower kernel: igb 0000:07:00.0: eth1: (PCIe:2.5Gb/s:Width x1) f0:2f:74:cc:72:94

I've updated the bios to the latest version and it still shows the same

Unless the MAC address for one of the NICs gets changed, I'm afraid both will never work.

How can i change it? I've tried with

ip link set dev rename_eth121 down
ip link set dev rename_eth121 address F0:2F:74:CC:72:93
ip link set dev rename_eth121 up

bot straight from the command line and putting it in "/boot/config/go" and then rebooting but nothing changed.

I've then tried deleting the /boot/config/network-rules.cfg file and after a reboot both eth0 and eth1 (it's no longer named rename_eth121) show up in NetworkSettings
It still seems to have the same MAC adress... i clicked the "port up" button but it does not take an ip and it shows "not configured" under interface description

Update: from this I did the cli commands again with eth1, enabled the port again, set IPv4 assignment to automatic and it works, I can have my container on the secondary WAN

tower-diagnostics-20251101-1902.zip

Edited November 1, 2025Nov 1 by giosann