First you can try to connect directly via https instead of http.
Other than that you can change the ports in your router by manually forwarding different ports to the well known ports on your WHS and then address your server with an address like http://myname.homeserver.com:88 (where 88 is the incoming port for the router in the example).
If all ports are blocked by your ISP or if the contract doesn't allow any server services to run and the ISP is not willing to cooperate with you as customer, a change of the ISP would be the only option.
Best greetings from Germany
Olaf