Splashtop Gateway needs certain ports be available to work properly.
- TCP Port 443, this is the main port serving the Splashtop services, which is configurable, please refer to How to change network port? on configuration.
- TCP Port 9080 on loopback
- TCP Port 5432 on loopback, this is for the embedded database to work properly
- TCP Port 7080 on loopback
- TCP Port 7081 on loopback
- TCP Port 5080 on loopback
As a general practice, we would suggest you, as the IT admin, need to make sure the port you would like to change to is not occupied, you can use Windows built-in resmon utility to check. From Windows search, type resmon, run resmon tool, go to Network, expand Listening Port, and check there is no other software listening on the those ports.