When connected to my VPN supplier using a Wireguard connection everything seems to work fine as long as I use the WAN (ethernet) connection. If I unplug the ethernet cable the router switch to the mobile connection (4G) as expected according to my failover settings. Still everything seems ok. But when I put the ethernet cable back into the router the mobile connection is still active and the traffic continues to use that connection instead of going back to the WAN connection.
In the log I can see that the router is switching back to the WAN connection but the traffic is still using the mobile connection.
If I disable the VPN connection the failover is working as expected.
What am I doing wrong here?