I’ve run into error 0x104 before; it usually means your PC isn’t reachable over the network. First, make sure Remote Desktop is actually enabled on the target PC and that it’s turned on (not sleeping), then check both devices are on the same network or that port 3389 is open if you’re connecting remotely. Also, allow Remote Desktop through Windows Firewall and confirm you’re using the correct PC name/IP. Most of the time, for me, it was either the firewall blocking it or using the wrong network profile (set it to Private).