Relay is losing connection to my radiator valves

Some times I lose the connection to all my radiator smartvalves. I take the Relay out of the plug and wait 5 minuts then I plug it in again and after an hour or two all the valves is connected again. I have tried to figure out how to change the relay, - I have a new device, but I can't finde som advice anywhere. Is there someone there have som experience?