"A connection to MultiTerm Server unknown cloud not be established" error message appears while trying to open a termbase.

When trying to open a termbase you receive the: A connection to SDL MultiTerm Server unknown cloud not be established error message. 



When trying to create a new termbase you receive the: Object reference not set to an instance of an object error message appears.

Open a Command Prompt by going into Start or Search, write CMD and click on Open. 
Enter the ipconfig /all command. If you have an IPv4 Address but you lack a Physical Address the issue is that the user has a VPN and SDL MultiTerm cannot function properly without a Physical Address.
In order to solve this issue you will have to disable the VPN connection and SDL MultiTerm will work properly.

This issue is caused by a defect, CRQ-21297, and it manifests itself if you are using a VPN such as NordVPN ,  ExpressVPN or Avast SecureLine.
If you are using a VPN you will not have a physical address but SDL MultiTerm needs a physical address for it to work properly.