Failover with wireguard / Wrong Route

Hello,
we are using an RUTX50 on a Remote Site with Firmware 00.07.17 and a Wireguard Connection. Failover is configured as primary wan and secondary mob1s1a1. Behind wan is another router (Fritzbox; 192.168.178.1) which is “online” but disconnected from internet.

We are connecting with wireguard to an endpoint ip, lets say this is 123.123.100.100.

When wan is offline and the failover switches to mob1s1a1, we cant connect with wireguard anymore. Problem seems to be the route for wireguard, it still tries to route over eth1 because the metric is lower. But why? Shouldnt the failover configuration use qmimux0 instead?

root@RUTX50:~# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default 192.168.178.1 0.0.0.0 UG 1 0 0 eth1
default * 0.0.0.0 U 2 0 0 qmimux0
10.0.0.0 * 255.255.255.0 U 0 0 0 cs_wg
10.0.40.0 * 255.255.255.0 U 0 0 0 cs_wg
10.0.40.1 * 255.255.255.255 UH 0 0 0 cs_wg
10.0.40.113 * 255.255.255.255 UH 0 0 0 cs_wg
10.198.153.212 * 255.255.255.255 UH 2 0 0 qmimux0
123.123.100.100 192.168.178.1 255.255.255.255 UGH 1 0 0 eth1
123.123.100.100 * 255.255.255.255 UH 2 0 0 qmimux0
192.168.110.0 * 255.255.255.0 U 0 0 0 br-lan
192.168.113.0 * 255.255.255.0 U 0 0 0 cs_wg
192.168.120.0 * 255.255.255.0 U 0 0 0 br-lan1
192.168.178.0 * 255.255.255.0 U 1 0 0 eth1

Hello,

The 7.17 firmware version was removed due to an issue with the Failover functionality.

Version 7.17.1 should be available soon, but in the meantime, we recommend downgrading your router to version 7.16.3. It can be downloaded here: RUTX50 Firmware Downloads.

We appreciate your understanding.

Best regards,

Hello,
Downgrade is not an option because it’s a remote site and I cant reconfigure the device, because the downgrade will remove the configuration.

Any ETA?

Configuration files will not be kept
Files will be erased. Uploaded firmware image version is older than current firmware version.