The way you describe playback being good for lower bitrate (sample rate and bit depth) files and worse the higher you go would seem to indicate a network issue. That is, the network is not fast enough to reliably support transferring the high bit rate files.
You could test this theory by trying to move both devices much closer to the wireless router or access point. Or by hard wiring both sides.
If the network speed is the problem, then you can fix it by either increasing your wireless network coverage, or by hard wiring both ends: The laptop and the CR511. Hard wiring one end might fix it, if the end you hard wire has worse reception than the other end. But if either end still has poor wireless reception, it's still going to have drop outs. Powerline network adapters are a decent choice, as they are more reliable than wireless and don't have a distance limitation.
You could try to use range extenders to get the wireless signal to be stronger near both end points, but this can be tricky to do correctly.
As for your laptop moving around a lot, here's a thought:
Maybe your MC server should be hard wired, sitting in one place all the time. Then you could control that server with JRemote on a tablet or phone. Or you could use TRemote to have a laptop PC remote control the MC server machine.
Just some ideas for you.
Brian.