The most common reason is that the remote side isn't running the app or has it minimized without an active session. Check that AnyDesk is open on the target machine and that the displayed ID matches what you're typing. If the address field shows "Connecting..." indefinitely, the remote device may be behind a restrictive firewall — ask the other party to allow outbound connections on port 6568.
This usually points to a corrupted installation or a conflict with antivirus software. Uninstall the client completely, clear leftover folders in AppData, then download a fresh build from the official site. If the crash persists, temporarily disable real-time protection — some endpoint security tools flag the remote-access process as suspicious and block it mid-launch.
The remote machine is likely running a full-screen app or a game in exclusive mode, which prevents screen capture. Ask the remote user to switch the app to windowed mode. On Windows, privacy mode may also be enabled — check Settings → Security on the remote side and turn it off.
Unstable sessions are almost always a network issue on one end. Run a continuous ping to a public DNS server on both machines to spot packet loss. If loss is above 2–3%, the problem is local infrastructure. Also check the power settings on the remote PC — sleep mode kicks in and drops the connection if the machine is left idle.
If the app shows no ID after launch, it failed to reach the discovery servers. Verify that your firewall isn't blocking the executable and that the service is actually running — on Windows, open Task Manager and look for the AnyDesk background process. Restarting the service through services.msc usually resolves this in seconds.