ND5 XS iRadio slow compare to Apple Tv

Hi Guys

I have 24 Mbps internet connection. I connected my apple tv to the ND5xs toslink digital input. When I stream at 320 kb/s (Linn Radio) on the ND5 iRadio (which is directly wired ethernet) it can't keep up and the buffer keeps dropping down until the radio cuts for 5 seconds. When I stream 320 kb/s from the apple tv to the ND5sx it plays just fine. 

Any ideas?

F