Ex3700 - 5 GHz not working (Google Fiber)

I have seen a number of posts about this on the community so I know this is a fairly common issue, however none of the solutions provided have worked for me. I installed the extender and got 2.4 ghz working just fine, but it won't let me connect to the 5 ghz band. Please understand I am in no way a computer expert and I have tried everything suggested on here from rebooting to updating the firmware (it already came with the latest version) to resetting the channel on my Google Fiber box. Nothing has worked. I have not, however, seen anything specifically posted about this problem with regards to Google Fiber so I thought I'd give it a shot. Any help would be most appreciated! Thanks!