Exchange 2016 certificate issues

Before, we had an exchange server with 2 NICs: 1 internal LAN, 1 external WAN.
The LAN was linked to our active directory domain server. It used an internal IP and hostname (mydomain.corp)
We have changed our network. We now use 1 interface, WAN only. (yes, it is secured, hosted).

However, since then, we keep getting SSL certificate errors when starting outlook.
We have an external hostname: https://remote.myfqdn.com/ , which runs a Geotrust EV certificate.
I have that as IIS binding.

The complaint however is about the exchange.mydomain.corp interface. (private).
This is a local hostname, and is locally used (used inside the domain).
Before, I could bind it to 2 seperate interfaces: One to my 10.0.0.0/8 interface LAN, and the other to the WAN.
Now, that is not possible.

How can I stop this annoying error?
redworksAsked:
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Adam BrownSr Solutions ArchitectCommented:
Most likely you just need to reconfigure your Active Directory Autodiscover SCP settings. http://wp.me/pUCB5-7X has more info.
redworksAuthor Commented:
Thanks for your response. I have already tried all of those, using powershell. Interesting article though. Same thing, but different approach.
Adam BrownSr Solutions ArchitectCommented:
Okay. If you hold CTRL and right click the Outlook window in the notifications area (By the windows clock in the lower right), it will show an option to test Autoconfiguration in the context menu. Run that test to get an idea of what exactly is failing.

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redworksAuthor Commented:
Great advise :)
It seems I forgot one of the many, many URLs.

The Internal HTTP MAPI URL was still going to mydomain.corp.
Fixed that, restarted services. Did not work. Rebooted server, worked!
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