Have you tried this:
Setup your Router like this:
IP Config, Miscellaneous:
Enable Web Access from WAN? Yes/No --> Yes
Port of Web Access from WAN: 1234
(1234 is just an example)
Enter this into your browser (from an external network <--Important)
http://www.the.external.router.ip:1234
It should work, but only from an external network not from your internal network.