Wired smart thermostat relay

My relay in the smart wired thermostat is working very intermittent. It worked great for two weeks but yesterday it not clicking any more. I reset the entire thing and ad it again when tried it out it worked and could hear click every time the relay changed possition. But only some minutes later it stopped worked again. The setting is R01. HC01 HW X Ek X

I also tried another (brand new unit) and it also works very intermittent sometimes it klicks sometimes not…? Total useless as it is now…

Any suggestion?