Exchange 2013 is the best when it's working but good god almighty is it a total pain when you screw one thing up. It's 2015 and the autodiscover service still is unbelievably difficult to get to actually work on external devices like iPhones, I was troubleshooting it and found my alternative subject names had the "AutoDiscover.domain.com" capitalized and of course naturally something like that which makes no difference in the real world causes the whole process not to work. So I went to Exchange admin center > Servers > Certificates and clicked "Renew" on the main certificate file and POOF!! Admin center no longer opens. Just like that. THANKS MICROSOFT!!!
Would love it if anybody can tell me why it is I'm too stupid to figure this thing out and how to fix it, and/or why clicking one friggin link can bring down all of Exchange administration.