Our Exchange 2010 running on Server 2008r2 SP1 has slowly having issues.
1. New users were unable to add exchange email on mobile phones, now older users are having an issue where they do not receive emails any longer.
2. OWA will not let you look at options or see previous emails without displaying the first read email, mainly no buttons work other than looking at inbox emails, BUT if "Light Version" is used - no issues that I can see aside from not having all the features.
My workaround was making users able to select "Light Version". I have looked around, recreated virtual directories but nothing has changed.
One thing I forgot to add, while using O365 Outlook, we are prompted for a password every time we load Outlook up. We are even asked for passwords of "Managed Full Access Permission" inboxes that a user has access to.