Port Conflict with NoMachine Display Service

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Affected Roles: Administrator

Related Digital Watchdog VMS Apps: DW Spectrum

Last Edit: May 12, 2025

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Port Conflict Notice

DW Spectrum Users may experience network connectivity issues when utilizing the third-party display service, “NoMachine”, encountering an error message like:

This is likely a result due to a port conflict between the DW Spectrum Server and NoMachine’s service. By default, both DW Spectrum and NoMachine use port 7001 for network communication. As no two devices may simultaneously occupy the same network port, user operation of DW Spectrum will be interrupted if the two programs continue to use the same port.

A solution for resolving this port conflict is to modify the DisplayBase key in the NoMachine server configuration file and specify a different value.

This article will outline how to modify the NoMachine server configuration file to resolve network conflicts with DW Spectrum.

NoMachine Port Modification

NoMachine Display Service Default Settings

The NoMachine display service uses a TCP port that is defined by the value set in the DisplayBase server configuration key + 6000.
By default, the DisplayBase is set to use “1001”, meaning that NoMachine will initially try to start the display service on port 7001 (e.g., 1001 + 6000 = Port 7001).

If this port is already in use, NoMachine will look for a free port by increasing the DisplayBase up to the value set in the DisplayLimit server configuration key.

This applies to both the display services that allow connections to the physical desktop as well as for each virtual desktop.

Resolving a Port Conflict

You can resolve a port conflict between the NoMachine service and DW Spectrum by modifying the NoMachine server’s DisplayBase value in the server configuration file.

1. The NoMachine server configuration file can be found in the following locations:

2. Open the NoMachine server’s file directory and edit the “server.cfg” file.
3. Locate the “DisplayBase” setting and change the key value.
   For example, changing the value from 1001 to 2001will start the display service on port 8001 (2001 + 6000 = Port 8001)
4. Restart NoMachine after making the adjustment to put the changes into effect.

For More Information or Technical Support

DW Technical Support:  866.446.3595 (option 4)

https://www.digital-watchdog.com/contact-tech-support/

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DW Sales:  866.446.3595                   [email protected]        www.digital-watchdog.com