Hello Patrick Cernko,
I have problems receiving some channels (ARD, ZDF,N3, DMAX) in good quality. Receiving other channels (SAT.1, RTL, Pro7, Das Vierte) works just fine.
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A friend of mine has problems on similar channels. We found out, that they result from interferences with his DECT wireless phone. Maybe you should check that by powering of the phones and base station?
I don't have any DECT phones in the house :-), and the W-LAN APs are far away. But thanks for the tip, I will keep it mind for the future.