Version 3.1.7 was released five years ago and the binary is no longer available. It has
dozens of serious security vulnerabilities that make it totally unsuitable for use. It makes your computer vulnerable to attack and does not provide a secure connection.
What makes you think only 3.1.7 is supported? Have your Uni's IT people contact me directly at my Gmail address, jkbullard, to discuss why they have told you that.
Please try Tunnelblick 3.5.8. If it doesn't connect, please post the diagnostic info you get from following the instructions
at Read Before You Post
(Now that I think about it, is is possible that you need 3.5.7, not 3.1.7? I can send that to you easily. It has some security vulnerabilities also, but not as many. Let me know and I can send you that.)