I've been noticing a recurring problem with my much beloved Lumia. Alot of the time the phone loses, or is unable to reestablish its data connection even though the phone reports up to a full signal. The only way I've found to solve it is to restart the phone.
I bought the handset outright and it's running on a sim-only contract on Tesco Mobile. I've installed and run the Network Setup app to ensure my APN and so forth are set correctly and yet the problem persists.
As you can imagine it's pretty annoying having to restart the phone alot when there's clearly a signal available.
Has anyone else come across this issue and if so is there a fix?
Have you tried taking your sim card out, ensuring it is fitted really well to the sim card holder and putting it back in?
I have had a few issues when I recently changed SIM card and doing that helped.