This issue may occur if secure communications are not configured as expected. Additionally, if older TLS versions are still enabled on the DDC, .NET Framework 4.7.2 may not default to using TLS 1.2.

The Cipher Suites required by Citrix Licensing needs to be configured on the DDC's. Additionally, the current version of Citrix Licensing does not support TLS 1.1 or TLS 1.0. If SchUseStrongCrypto is not set to 1 in the registry, .NET 4.7.2 may not default to TLS 1.2 even though the framework version supports it.

Ensure that the DDC has the required cipher suites that the license server expects.

https://docs.citrix.com/en-us/licensing/current-release/license-server-getting-started.html#cipher-suite-order-and-requirements

Additionally confirm that TLS 1.2 is enforced by configuring the SchUseStrongCrypto setting in the registry.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
"SchUseStrongCrypto"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v4.0.30319]
"SchUseStrongCrypto"=dword:00000001

The LAS Supportability Tool indicates that all tests are passing with no reported errors.

https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX696351&articleURL=Citrix_LAS_Health_Network_Pre_Check_Utility_Guide