Default {Q} Losing mobile signal

I have One S S4

Few weeks ago, the phone started to loose mobile network and never get it back until I remove sim and put it back.
After a period of time that did not work. I had to restart the phone to get network. Turning Airplane mode on and off does nothing.

I decided to unlock the device and I installed Cyanogen mod - The last stable version - I thought this could resolve the issue

I am facing the same issue

Is it hardware or software issue?
and How can it be resolved