Hello,
With Mentor Standard Licensing (v2015_2) installed on the server, run the following command to see if it reports the required 6.65 version (see screen-shot).
C:\MentorGraphics\Install\pcls\drivers\haspdinst32.exe -info
If the version reported is older, run 'Mentor Graphics > Mentor Install' to launch the Mentor Install Program, navigate to 'Manage Licensing > Install Hardware Key Drivers', and install the updated drivers.
Cheers,
Andrew