Can't connect to activation server

I am using SDL Studio 2017. It has been working fine over years.

Last week I uninstalled an even older version (Studio 2011, I think) that was using disk space.

Now my 2017 installation asks me to activate the license.

When entering my license I receive the following error message (translated from German):

The connection to the activation server could not be established. Check the address of the activation server. No SSL/TLS channel could be created.

Please help.

Thanks Arnd

emoji