Default Data connection dying


I have a problem with my Ascend P6. It used to work fine, but these days more and more often the GSM data connection just stops to work. It is still turned on, but data are just not transmitted. Turning it off and on does not help, neither switching on and off the air plane mode. The only thing which helps is to restart the phone.

I have had not changed any setting, I have still the original Android (4.2) and no crappy software installed, just same games.

Please, can you help? Can it be fixed, or is it a hardware problem? I imagine in the service centre they would just say they didn't reproduce the problem and/or perform a factory reset at best. And I would be without the phone for like a month, which suc*s.