After upgrade to PAM 4.2 attempts to access an RDP server via the PAM client fail with the following error:
SSL connection error insufficient_security(71).
The RDP server was running Windows release 2008 R2, which is no longer supported by PAM or by Microsoft.
Upgrade to 2012 R2 was sufficient to resolve the problem in this case, but the server was upgraded further to Windows 2022 to be fully supported by PAM and Microsoft.
Documentation page Supported Environments lists the Windows releases supported by PAM 4.2 for access sessions and credential management. To check this for other PAM releases, replace "4-2" in the URL with another release, such as "4-1-8", or use the Version dropdown list near the top of the page to switch to a different release.