I'm trying to use an older HP laptop as a second display for my Dell laptop with Spacedesk. The server is installed on the Dell and the viewer is installed on the HP, but the viewer only reports "Cannot detect Server!" Both devices appear to be connected to the same network, and temporarily disabling the firewall didn't help. I later realized the connection is through a mobile phone hotspot rather than a normal router or Ethernet. Could the hotspot be preventing the laptops from discovering each other?
2 Answers
Try connecting both laptops to the same home router and check that they’re on the same local network, not a guest network. You can also test with Ethernet on both machines. A normal network should allow the viewer to find the server, while phone hotspots often don’t support this kind of device-to-device connection.
The mobile hotspot is probably the issue. Many phone hotspots let devices access the internet but isolate them from one another, so the Spacedesk viewer can’t discover the server. Test both laptops on the same regular Wi‑Fi router, or connect them directly through Ethernet if possible. If it works there, Spacedesk itself is fine and the hotspot is blocking local-device communication.

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