@etxmsol I think you might be right about to strong signal.
I just tried changing the MY_RF24_PA_LEVEL from RF24_PA_MAX down to RF24_PA_LOW and RF24_PA_MIN. With RF24_PA_MIN it worked. 
I will try again with increasing distance and increasing the level when needed for my purpose.
@gohan I would like to leave the weather station reprogramming as the last option since it was built in the v1.5 period and calibrated. Never try to repair a working device
In general I would like to develop a solution where display nodes can be added to the network not having to change other nodes for that. The independency of using display nodes without having to change sensor nodes would be great to achieve.
@mfalkvidd I'll try to find out how to request data from the gateway/controller of a specific node. As long as the Pimatic controller is showing the data there must be a way to get it from there. Search the Pimatic forum for now.
@Yveaux thanks for your reply.
I will update MySensors to v2.0.0 when I believe my Control software Pimatic can handle all (there are some issues with sensors I have built with v2.0.0 and are running well on v1.5.4).
So I will give it some time to evolve for now.
@mfalkvidd I have found someone with the same issue, using a different board version 0.9 vs 1.0.
WIFI Gateway NodeMCU 0.9 always reset
@bigjimjeedom was using firmware 2.0.0 ending up with the same error. Not solved in this thread.
@gohan thanks for the info.
I'll look into it and see if the transition is worth while.