To make your computer accessible remotely from Screens, Screens Assist attempts to open a port on your router using UPnP—a feature supported by most routers.
If Screens Assist is unable to open a port, it will notify you and explain the issue. In most cases, this happens because UPnP is disabled and simply needs to be turned on.
Please refer to your router’s documentation for instructions on enabling UPnP.
Keep in mind that some mobile network routers (such as 5G routers) may not support UPnP. In such cases, Screens Assist may not function properly.