And how do users connect to your port if your VPN-WAN doesnt have a port forward?
Same problem at a different point in the connection.

That still won’t work. Either the forwarded port is getting blocked by Mullvad (which is bad) or you’re bypassing Mullvad to use the forwarded port (which is really bad). You’ve essentially roped yourself into a double-NAT situation, where your router has a forwarded port but the router behind yours (the VPN server, which you have no control over) doesn’t.