Comment 2 for bug 1499342

It is difficult to say what might be happening. list-modems shows that NetworkRegistration mode is automatic, and the modem is registered to symio's Edge network (2G), although the preference is umts.

The issue here is that we do not have that much control over the modem FW: if there are 2 available networks, and one of them is seen by the modem as a roaming network, the modem will probably register to the other network even if it has to use a worse technology.

Please try going to

SystemSettings -> Cellular -> Operator -> Operator

and then manually select the O2 network and check if you can register in this way.