I have to access repository.maemo.org via an anonymizer proxy, there'ssomething with my provider's IP that's going wrong with the repository site. There's a thread in bugzilla, https://maemo.org/bugzilla/show_bug.cgi?id=445
about this. IMHO you've some problems with your provider/router conf, at first sight I don't think it's a 770 problem.
If I like to use application manager directly, I have to use links via the anonymizer or download packages via phone connection (or use someone's friends WIFI...), otherwise I get an authorization required reply.
HTH