I have a somewhat bizarre problem when trying to access my Fritz!Box 7340 remotely via a Telecom XT 3G data connection. Remote access is enabled on the Fritz!Box, and when I tried accessing it remotely via https://, I get a prompt for the remote access username and password. I entered it and I then get prompted for the "local" password for the Fritz!Box. This is where things gets stuck - upon entering the correct local password, the password prompt/page keep reappearing - it wouldn't log me into the Fritz!Box.
Initially I thought it was a problem with my Fritz!Box, but I later discovered that the problem only appears when I tried accessing via a Telecom XT 3G data connection - either on my iPad (via 3G), iPhone, or even on my laptop tethered to my iPhone. It works fine if I am accessing it either via other ISP, I.e. using wifi at a friends place, public wifi access, o even on my same laptop but using a Vodafone 3G USB data stick. Simply put it doesn't seem to work as long as the data/Internet access is via XT 3G.
I thought this is pretty bizarre - has anyone seen anything like this? Any ideas what could be wrong?