Question Loosing connection on android 4.4.4

Currently I'm experiencing the following annoying problem:
My phone keeps loosing connection to my provider (KNP, NL) in areas with normally full signal strength (city center, rural areas everywhere). When I put my phone in airplane mode and switch airplane mode off again, the connection is back.

After posting this problem on a Dutch (tech)blog I got responses that people experience the same problem with their Nexus 5.
This error happens with different Roms.

Anyone with tips / more insight?