The udp server (v1.0.1.8) is receiving data and writing out of the uart, one packet on average every 1/66 seconds. Every 2 minutes the time increases by around 50ms I guess (it is almost impossible to view this time change, but I know from program analysis that something is happening, but I have not actually observed it).
Is it perhaps the server doing some sort of client scan or ip address check causing a brief delay ?
For me there is no point in checking the other environments described, since this is not how the modules are used in the system.