Hi!
I have this same problem. After the latest software update my phone seems to randomly loose mobile network connection. Sometimes the connection is lost several times a day…
Sometimes I notice this, because the phone asks for PIN code. Lately though I have just gotten noted by colleagues that calls to me are forwarded directly to the answering service. When this is the case, if I try to disconnet the SIM-card from the SIM management settings, the phone just freezes and the only option is to reboot.
I’m pretty sure it has nothing to do with the touchscreen sensibility, since it also happens when my phone is lying on the desk. I also haven’t been able to find any other reasons for this behaviour. It seems totally random. Sometimes it happens several times a day, sometimes not.
I really love my fairphone, but this is a rather inconvenient problem, since I prefer to be available during the work day…