POSTSCRIPT: So we discovered on switching off everything (after stopping and disconnecting the base first) that we go back to square one again with the same problem re-emerging on restarting the base-rover machine, and the controller waits for a RTCM signal to be passed with none being apparently sent - even though the tx on the radio is flashing. We then stopped and switched off everything (again - for the nth time) and swapped the T2s (as base and rover - un- and re-pairing them using Nethub). Lo and behold the base-rover works beautifully on restarting only to loose the plot when you switch off everything and restart. No settings are changed in the interim (of course). We are actually starting to get rather fed-up. We have spent many many many hours with this sytem, and it's one thing after the next. I have a lot of other things to be doing besides this. This is not sustainable. What to do? Thx.