Robot studio 5.14.03 not getting a license from new SLP server.

I have just activated a new license server, and the version of Robot Studio I have in our teaching labs can no longer obtain a license.
I had this issue before and installing 6.03 on the PCs fixed the issue, but this no longer seems to fix the issue.

I have 3 versions installed on my PC ... trying to fix the issue and versions 5.61 and 6.03 can both obtain a license with no issues

but 5.14.03 says "Network license not available"

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RobotStudio .NET exception: Canceled

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Base exception: NotLicensedException

Canceled

   at Microsoft_Licensing_Permutation_6e3db_2_0_3_1_1925_4kh.A(Assembly A_0, Byte[] A_1, IExecutionEngineParams A_2, Boolean A_3)

   at Microsoft_Licensing_Permutation_6e3db_2_0_3_1_1925_4kh.A(Assembly A_0, String A_1, IExecutionEngineParams A_2)

   at Microsoft.Licensing.SLMRuntime.InternalExecuteMethod(Assembly declaringAssembly, String SVMMethodId, IExecutionEngineParams paramsReader)

   at Microsoft.Licensing.SLMRuntime.ExecuteMethod(Object obj, String SVMMethodId, String _assemblyId, Object[] args, Type[] genericTypeParams, Type[] genericMethodParams)

   at ABB.Robotics.RobotStudio.LicenseValidator.AcquireExecute()

   at ABB.Robotics.RobotStudio.LicenseValidator.Initialize()

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any help would be appreciated.

Regards,

Neil