For me I ran into issues with my ISP blocking port 80, to get around this I have the router forward port 8080 to my WHS box on port 80.
This way when I come in via http://mywhsdomain:8080
it then resolves internally to port 80 on the WHS box with no problem.
My ISP (Fairpoint in NH, ex Verizon FIOS), doesn't block 443 so I'm able to use SSL without issue but perhaps your ISP is blocking 443 as well so you could try redirecting that?
For what its worth, WHS's remote access setup never seems to work PNP wise so I've always had to manually create the port forwarding rules on my router.