XfW relies on the .net framwork's configuration to choose which TLS versions to use when connecting to the CMS.

By default, Windows enables only TLSv1 connections. TLSv1.2 can be enabled with a registry key as described in the FAQ here:
https://community.xibo.org.uk/t/enable-tls-1-2-strong-crypto-in-windows-net-player/7091

Investigate if it can be switched on in code instead, or if we need to make the installer set that too.