LiveUpdate starts downloading - then timeouts

Hello,

I am having a strange problem on SBS 2011 (Windows 2008 R2) with LiveUpdate and SEPM.
The download begins but then timeouts. No content has been downloaded for a month now.

Downloads from the Internet (using Chrome or IE) starts but after a few 100 KB the speed decreases and shortly after the download progess hangs.

Speed tests using several websites does not show any problems (8.5Mbps/10Mbps).

Any ideas what could be causing this behaviour?

Regards

Thomas