Upgrade to 2.4.5 Default Route Switches to OpenVPN Interface
Since I have upgraded to 2.4.5 the default route of the openvpn s2s peer (client) switches from wan to the openvpn interface.
If you have the client OpenVPN assigned as an interface it will create a gateway and that may be chosen as default.
Set the WANGW as default in System > Routing > Gateways rather than automatic.
That could also have happened in 2.4.4p3 so it's probably unrelated to the upgrade.
Sry my fault. It was on automatic, but why does this happen only since 2.4.5?
Nothing has changed there in 2.4.5 as far as I know. It's likely just luck it only happened now.