UFT 12.53 Compatibility with Windows Server 2016(for concurrent license)

We have Windows 2016 server on which we have installed UFT 12.53 and trying to connect the same with concurrent license. But getting error “License server is not available”.

License Server Version : 8.3.0

I have read that it is not compatible with UFT 12.53(as per PAM),So tried installing UFT 14.0, but no luck. Same issue persist.

We can’t update our license server.

Please provide some solution.