After an upgrade on one of my lab routers from 2026.06.10-0053-rolling to 2026.09.09-0029-rolling the router became unreachable.
I had eth0 and eth1 interfaces prior to the upgrade, after I logged in via a virtual serial console I found that interfaces were being renamed to eth2 and eth3 instead. Of course configuration was still for eth0/eth1 so that failed to apply.
fabrizzio@PRG1NAT1:~$ show int
Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
Interface IP Address MAC VRF MTU S/L Description
----------- -------------------------------- ----------------- ------- ----- ----- ------------------------
dum0 192.168.255.32/32 fe:9d:18:73:ea:df default 1500 u/u Loopback / Tunnel Source
2a0e:8f02:21d1:ffff:caca::32/128
eth2 - 22:88:7a:44:a1:cc default 2000 u/u
eth3 - 26:a7:02:74:83:43 default 2000 u/u
lo 127.0.0.1/8 00:00:00:00:00:00 default 65536 u/u
::1/128
fabrizzio@PRG1NAT1:~$ show log | grep vyos_net_name
Sep 09 11:18:51 vyos_net_name[607]: e3 (22:88:7a:44:a1:cc) -> 'eth1'
Sep 09 11:18:52 vyos_net_name[611]: e2 (26:a7:02:74:83:43) -> 'eth0'kernel logs
[Wed Sep 9 11:18:46 2026] sd 0:0:0:0: Attached scsi generic sg0 type 0 [Wed Sep 9 11:18:46 2026] sr 2:0:0:0: Attached scsi generic sg1 type 5 [Wed Sep 9 11:18:46 2026] Free page reporting enabled [Wed Sep 9 11:18:47 2026] input: PC Speaker as /devices/platform/pcspkr/input/input4 [Wed Sep 9 11:18:48 2026] Process accounting resumed [Wed Sep 9 11:18:51 2026] virtio_net virtio3 eth1: renamed from e3 [Wed Sep 9 11:18:52 2026] virtio_net virtio2 eth0: renamed from e2 [Wed Sep 9 11:19:02 2026] pim6reg: entered allmulticast mode [Wed Sep 9 11:19:02 2026] NET: Registered PF_PACKET protocol family [Wed Sep 9 11:19:04 2026] virtio_net virtio3 vyeth3: renamed from eth1 [Wed Sep 9 11:19:04 2026] virtio_net virtio2 vyeth2: renamed from eth0 [Wed Sep 9 11:19:04 2026] virtio_net virtio3 eth2: renamed from vyeth3 [Wed Sep 9 11:19:04 2026] 8021q: adding VLAN 0 to HW filter on device eth2 [Wed Sep 9 11:19:04 2026] virtio_net virtio2 eth3: renamed from vyeth2 [Wed Sep 9 11:19:04 2026] 8021q: adding VLAN 0 to HW filter on device eth3
fabrizzio@PRG1NAT1:~$ configure
WARNING: There was a config error on boot: saving the configuration now could overwrite data.
You may want to check and reload the boot config
[edit]
fabrizzio@PRG1NAT1# show interfaces
dummy dum0 {
address 192.168.255.32/32
address 2a0e:8f02:21d1:ffff:caca::32/128
description "Loopback / Tunnel Source"
}
loopback lo {
}
[edit]
fabrizzio@PRG1NAT1# load
Load complete. Use 'commit' to make changes effective.
[edit]
fabrizzio@PRG1NAT1# compare
[interfaces]
+ ethernet eth0 {
+ address "172.27.18.34/30"
+ description "To PRG1CR5"
+ }
+ ethernet eth1 {
+ address "172.27.18.38/30"
+ description "To PRG1CR6"
+ }root@PRG1NAT1:~# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 2000 qdisc mq state UP mode DEFAULT group default qlen 1000
link/ether 26:a7:02:74:83:43 brd ff:ff:ff:ff:ff:ff
altname enp0s18
altname ens18
3: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 2000 qdisc mq state UP mode DEFAULT group default qlen 1000
link/ether 22:88:7a:44:a1:cc brd ff:ff:ff:ff:ff:ff
altname enp0s19
altname ens19
4: pim6reg@NONE: <NOARP,UP,LOWER_UP> mtu 1452 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/pimreg
5: dum0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/ether fe:9d:18:73:ea:df brd ff:ff:ff:ff:ff:ff
alias Loopback / Tunnel SourceNote - I had no hw-id configured on those interfaces, they're just the default ordering (I use proxmox - so virtio interfaces, and I relied on virtio0 being eth0... and so on).
If I have hw-id configured on the interfaces prior to the upgrade, it works fine, interfaces remain as eth0 and eth1