i did some investigation into this and it looks like something has changed, either unraid related, docker related or wireguard related, in any case this is the curent state of things:-
vpn - custom bridge vs 'bridge'
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with custom bridge with specific ip
wireguard
can access the webui from lan
cannot access the webui from remote over vpn
cannot access the webui from port forward
openvpn
cannot access webui from lan
cannot access the webui from remote over vpn
cannot access the webui from port forward
with 'bridge
wireguard
can acccess the webui from the lan
can access the webui from remote over vpn
cannot access the webui from port forward
openvpn
can access the webui from lan
can access the webui from remote over vpn
can access the webui from port forward
so as you can see from the above, best connectivity is from 'bridge' mode using openvpn, second is 'bridge' mode using wireguard, however accessing the web ui over a simple port forward when using wireguard does not work, even in bridge mode.
so you currently have it set to wireguard with a custom bridge, which will get you access to the web ui, but will not permit access to the web ui when remoting in over vpn (at least not in my testing it didnt!).