fold is not connecting even though it has an ethernet cable
Assuming that you can access the internet for other things, I would check that your router can see your device, whatever it is, and if so whether the router’s firewall is blocking the attempted connection?
If you are running on your main computer, the firewall on your security software (anti virus) might also be blocking attempted connections. You need to check the logs of both your security software and your router to see if they give any clues. Does the app come up OK and if so, what does the log on there tell you? You need to be in advanced view -> tools to see the Boinc event log.
Does this help?