Ideally we are looking to complete the following:
         1) User changes field in Contact object
         2) SalesForce authenticates to our site with oAuth2
         3) Field(s) from Contact object are updated in our database.
Currently this works starting from Postman:  I can authenticate to our endpoint, receive and store the token and update the data to our endpoint.

I have the setup in Sandbox.

I have an APEX trigger that kicks off on an update to the Contact object which does a callout to and APEX class.

I have an Auth Provider setup.  The provider type I selected is Open ID Connect - since I did not know what else to pick.  The URL Suffix is 
My_Auth.  The consumer key and consumer secret are filled in the same as on Postman.  The Authorize endpoint and Token endpoint are https://oursite.com/token.

I have a Named Credential setup with the name My_Endpoint.  The url is the full token url(https://oursite.com/token).  It is also setup with an Identity Type of Named Principal, Auth Protocol of oAuth 2.0 and an Auth Provider of My_Auth.

When I change a field in the Contact object, everything kicks off - but I get a Read Time Out error.  

Can anyone help me with debugging further to see why I cannot get the token returned and/or why it does not seem to hit the token endpoint?