If you're connecting to a computer on a corporate, academic, or other network outside your personal control, you may encounter challenges using Screens, Screens Connect, and Screens Assist. These networks, often classified as "semi-public," typically enforce stricter security measures than home networks and may not support consumer-friendly services like UPnP (Universal Plug-and-Play) and NAT-PMP (Network Address Translation-Port Mapping Protocol).
To enable automatic port forwarding from the router’s public network port to the private network port of the target computer, Screens Connect and Screens Assist rely on UPnP or NAT-PMP. If these protocols are unavailable, manual port forwarding configuration on the router is required. If you don’t have administrative access to the router and port forwarding isn’t configured, Screens won’t be able to establish a connection with the target computer. In such cases, contacting the network administrator may be necessary.
Tailscale
An alternative solution is to use Tailscale with Screens, which does not require opening any ports. You can find detailed instructions in this article.