I may be wrong about this, however...
I have noticed that when setting up the WireGuard client in WiCAN Pro, you are only allowed one network CIDR definition in the "Allowed IPs" field. Essentially, if you type in multiple entries, only the first one will be implemented.
This makes it very restrictive if you want split tunneling to work properly,
The only workaround is to use 0.0.0.0/0, which may not always be ideal.
I have set up other clients (eg, Android) and you are allowed multiple CIDR entries in that field.
Ron