You can change the network port the Splashtop Gateway serving, it's quite easy.
Log in to Gateway's management console with the system admin, go to System > Network, the Port section shows the port that Gateway is currently serving, click Change Port will allow user to input a new port and apply.
1. Changing port will automatically restart Gateway service, it needs like one minute to be ready again.
2. If you already have Streamer deployed or On-Prem client app logged in, these Streamers and On-Prem client apps will be logged off, due to the port change, you need to specify the correct IP:Port in the Streamer and On-Prem client side to log into the Gateway again. 443 is the default port, which can be ignored.
(Input IP:Port in the Gateway field to deploy)
(Input IP:Port in the Gateway field to login)
3. 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 chosen port.