which hub do you have? any error codes shown in the app?
start with following the guide in this thread: https://community.smartthings.com/t/troubleshooting-smartthings-hub-2018-and-aeotec-hub/298332
have you tried on a different network such as a family member or friend since you tried the port on your network?
post in the thread I linked as staff are actively monitoring it.