I'm in the middle of migrating from Ex2007 to Ex2013. This is a simple setup with a single server running Ex2007. Port forwarding on the firewall redirects incoming port 443 to Ex2007 for activesync/owa, etc. Exchange 2013 has been installed and configured. Both are coexisting fine. I've moved one mailbox. Exchange 2013 has a valid wildcard SSL certificate.
Now, I change the port forward on the firewall to direct 443 to the new server instead of the old. Remote Connectivity Analyzer connects and verifies that everything is fine for both the migrated mailbox as well as mailboxes that are still on Ex2007. However, for all mailboxes (the migrated one as well as all of the ones still on Ex2007), iPhones repeatedly prompt for password. Entering your password does no good. If you remove the account from the iPhone and add it back then everything is fine. The problem is that we have about 100 phones and doing this to each will be a nightmare. I changed port forwarding back to the old server until we can figure this out. Has anyone else run into this issue? To emphasize, ActiveSync is working fine. I have also found that, instead of removing the Exchange account and adding it back to the iOS device, you can just go into account settings, change a field and save, causing the iOS device to re-verify. After that, you are fine. Any ideas?