I can’t connect to my Mac using my PC, the message was connection timed out.
This is very likely a firewall problem. Try disabling the firewall or check that the firewall is not blocking port 4000 (this is the default port used by NoMachine).
Every time I connect to the PC, “The connection with the server was lost. Error is 54: connection reset by peer” pops up.
Logs would be useful for the problem connecting from Mac to Windows. We would need sets from both sides, so client logs from the Mac machine and server logs from the Windows PC. You can submit them here or send them to issues using the title of your topic.
Instructions on how to gather logs are available here: https://www.nomachine.com/AR10K00697.