Unable to retrieve license from server

Hello,

we are currently migrating our host wich runs the trados license server.

To do this, we need to get the Trados License Manager running on one of our local clients which runs Windows10. 
I was able to get the license manager installed and activate the licenses on the new machine, but when one of our clients wants to retrieve a license we get an error message "unable to retrieve license, please retry".

The old server is a Server 2012, the new server is a standalone win10 machine.

Both devices are on the same subnet, so I assume something in windows firewall is blocking this.

Does anyone know which ports I need to open to get this running?

Kind regards

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