RPC over HTTPS does not work anymore- FIXED!

Recently I have had a problem with RPC over HTTPS. It has worked for years, but suddenly users told me it was not working. If they had told me when I would perhaps have found it quicker but instead, I had to wade through all the documentation and goodies.

For I tried to re set it up, that did not work. I tried reinstalling and that did not work.

Eventually I founds this cool tool online Test Exchange Connectivity and when I ran this test, and expanded the errors I was finally pointed in the correct direction.

In the IIS config of RPC. I click properties, and I saw that "Accept client certificates" was ticked. I unticked it and just like that it worked.

By the was cool trick I learnt to check the connectivity was to Ctrl+right click on the Outlook Icon in the right of the tool bar and the select Connection Status...

It then tells you TCP/IP or RPC.