Problem Streaming 16Bit/44.1kHz flac Radio

Good evening

I have installed Musicbox based on Mopidy on my Raspberry Pi. Everything works fine except streaming of high-res radio-stations.
For example I tried to listen to http://sr7.inmystream.info:9100/stream.flac which is 44.1kHz, 16Bit, flac.
But the request ends in a timeout:
2016-02-17 16:15:45,852 - WARNING Problem looking up http://sr7.inmystream.info:9100/stream.flac : Timeout after 20000ms
As you may see, I have increased the timeout to 20s, but it doesn’t help.
With VLC it works fine.
Mopidy version is 0.19.5s

Any hints are welcome!
Roland