Had nothing but problems with pro box past few months (non ip mode)failed recordings picture glitching ,having checked and tested tv Ariel by running old freeview box on it which works fine,so i put the box into ip mode thinking that would improve things ,but just as bad if not worse ,i.e recording show 30 min about half way through it will stop and say end of recording and wont play any further,i done soft reset hard reset and factory reset made no difference,if Bt did`t own the box would took a hammer to it,wish never upgraded to pro box nothing but bugs an fed up getting earache off the other half over it.
I can only suggest calling customer services [0330 1234 150] as there is the potential the STB is faulty and they hopefully send an exchange replacement given you have performed all the obvious troubleshooting methods I don't think there is much left to test.
Have you confirmed the STB software is upto date? Although I believe during a factory reset this check is completed if there is connectivity.
I have just sent mine back as it would not work with my Bt broadband with 40 mps. I even had an Ethernet cable from my hub to the back of it. Bt could not help with numerous switch on/off routines so luckily I had kept the old set top box which is now working fine.