The actual APN (access point name) is internet.telekom based on this Liste aller Telekom Mobilfunk Zugangspunkte (APNs) | Telekom hilft Community and you appear to be currently using internet.t-mobile.
It looks like the userid and password are "telekom" and "tm" respectively.
Having said all that, I don't really think it will make much differences because it appears to have got past that stage anyway.
If fails when connecting to "community.beelogger.de on port 443