Hi, go to MagicInfo Server -> Device -> Notifications. There you can see if there is some error, problems etc.
If there is no notifications and no errors, it is possible that you have a demo license that get expired.
In case that you use 7002 port as ppjin comented, for communication with new S7 and up, you need to replace TLS key file and modify setup file. It is not a user friendly procedure.
Regards,