The "M" is marked for different region only, for open market firmwares. The "M" marks a provider in Australian firmwares. The Australian Telstra phones are not compatible with the Euro firmware. Do not worry about that as it does not affect you
NPS does not function properly, and has some unusual reactions with the phones. I have seen this pop up on several model, you should reinstall NPS on your computer, and hard reset the phone. This should clear the problem in the connection hanging.