How do I check if another program is using the same port as UltraVNC?

Datto RMM installs and uses UltraVNC (UVNC) when using the VNC functionality within the Agent Browser. Problems may occur if another version of VNC is installed on a device, as whichever VNC version starts up first will use the required port (port 5900) and deny any other VNC access to the same port. To check if another program is using the same port as UltraVNC, follow these steps:

  1. On the affected machine, open a Windows Command Prompt session.
  2. Type the following command:
    @for /f "tokens=5" %v in ('netstat -nao ^| find ^":5900^"') do @tasklist /FI "PID eq %v"
  3. If the output is anything other than WINVNC.EXE, UVNC is not accessing the required port. A conflicting version of VNC is likely installed. Contact Datto RMM Support for assistance. Refer to Kaseya Helpdesk.

Additional resources