Quote from smove :

UPDATE: Not so well. After investigating a bit I found out that port forwarding is simply not possible according to my internet/cable provider (which is Unitymedia btw.). The reason is IPv6 and DS-lite. Hosting a server here seems to be possible only with having a business rate ...

Germans and internet, still completely crazy. I wouldn't have thought ISP was blocking..

There are providers which are not blocking this though... Mine doesn't, but I can't do anything here because too far from DSLAM and no G.vector yet -and- no tv cable exists ... Ppff..

Only option is hybrid stuff from Telekom but I don't trust that this works because the mobile network also is completely useless