In T5324#151418, @greenpsi wrote:

I think I found the real problem:

The 62-temporary-interface-rename.rules udev rule runs in initramfs before the USB modem is detected:

Jun 30 14:32:11 vyos kernel: r8169 0000:03:00.0 e3: renamed from eth1
Jun 30 14:32:11 vyos kernel: r8169 0000:02:00.0 e2: renamed from eth0

[...]

Jun 30 14:32:11 vyos kernel: usb 1-1: new high-speed USB device number 2 using xhci_hcd
Jun 30 14:32:11 vyos kernel: ata2: SATA link down (SStatus 4 SControl 300)
Jun 30 14:32:11 vyos kernel: ata1: SATA link down (SStatus 4 SControl 300)
Jun 30 14:32:11 vyos kernel: usb 1-1: New USB device found, idVendor=12d1, idProduct=1f01, bcdDevice= 1.02
Jun 30 14:32:11 vyos kernel: usb 1-1: New USB device strings: Mfr=2, Product=1, SerialNumber=0
Jun 30 14:32:11 vyos kernel: usb 1-1: Product: HUAWEI HiLink
Jun 30 14:32:11 vyos kernel: usb 1-1: Manufacturer: HUAWEI

So the modem does not get renamed to eX and thus, if the modem has an ethX name that conflicts with the configuration from the 65-vyos-net.rules udev rule, the renaming of the interfaces from eX to ethX fails because a duplicate already exists.

So in conclusion, if VyOS wants to support USB Ethernet devices, the 62-temporary-interface-rename.rules udev rule should be deferred until the USB devices are detected or something like that.

I think I found the real problem:

I found the following log in /run/udev/log/vyos-net-name from the vyos_net_name python script:

In T5324#151306, @Viacheslav wrote:

e2 it is a temporary name to rename ethX in correct way
You have to use “ethernet ethX address x.x.x.x”