It's possible to update a NoMachine installation from remote in any of the following ways. Note that when the upgrade is made via a NoMachine connection, you will be disconnected because the upgrade requires to stop all the NoMachine services and will restart them once completed. Wait a moment and try to reconnect.

1) by automatic updates from the NoMachine repositories

In order to update the installation by using the automatic updates, open the UI and access the Settings -> Server -> Updates panel or  -if you have only NoMachine Enterprise Client installed - Settings -> Player -> Updates

In the Updates panel, click on 'Check now' and proceed to update.

2) from command line via SSH

As an alternative, connect for example by SSH and update the installation from command line. Detailed instructions are available in the following articles:

For Windows: https://kb.nomachine.com/AR07K00682
For macOS: https://kb.nomachine.com/AR07K00683
For Linux: https://kb.nomachine.com/AR01L00775

Some tips for upgrading via automatic updates
- Consider to have a backup method to access the machine from remote, for example via SSH.

- Before updating the installation, it's advisable to ensure that all users are disconnected. To do that, you can for example shutdown the server before proceeding with the automatic updates.