I have always used AOKP and have usually had success in flashing the new version of the ROM over the current version without having to do a clean wipe or wipe data and cache or wipe dalvik cache. It usually just works.
I can remember recently a few weeks ago I was streaming a podcast over 4g in the car and in the middle of the podcast the data connection just died it went away and I lost the audio stream.
I live halfway between Baltimore and Washington DC so I am pretty sure I am in a strong 4g zone and should have no issue pulling in a mobile data signal.
Should I try wiping data and cache along with dalvik? I am not quite sure what those are either.
For what its worth I did wipe data and cache as well as dalvik, this did not solve the problem. I tried turning data on and off and this did not fix the problem.
I followed that with a factory wipe. This did solve the problem, or so I thought. I went to a baseball game and had a 4g connection at the game I was able to download a few apps as well as post a photo to facebook. Then went out to eat after the game and still had 4g. I got home and the connection was handed off to WiFi. I disabled WiFi just to see if 4g would kick in, but it didn't at all.
So now I am back to no 3g/4g at all. I don't remember this happening in other versions of AOKP that were based on 4.2.x and 4.3.x and early versions of 4.4.x. This all started within the last 2-3 nightly builds.
Is there anything I can submit from the phone to help troubleshoot this?