Hi Joe Miller,
Quick question:
Are users being forced to re-enter guest pass every 30 minutes?
I don't have a ZD at my hand to check this and If answer to above question is yes, then i vaguely remember a setting while creating guest pass where you configure the user to re-auth by entering guest pass key every X minutes. Start by disabling that option and create a new guest pass and see if while testing you are being forced to re-auth again after 30 mins or not.
Hope this helps and cheers