Data Overtime - No Stream for 20s

Hello all,

Please can anyone give me some advice on where to go next in problem determination.

Hardware:
NVR = DS-7608NI-I2/8P firmware V4.22.005 Build 191208
Cameras = 5 x DS-2CD2155FWD-I firmware V5.6.3 Build 190923
CAT6 cable and all cameras using PoE

System installed since August 2017, upgraded firmware on a regular basis and no real problems to talk about. About a week ago 1 camera started to randomly disconnect with main error message "Data Overtime - No Stream for 20s".

I...

Data Overtime - No Stream for 20s