ADFS Proxy Service Unavailable Error - 503

[Squan_JRP]

Have O365 setup with ADFS for SSO and external authentication is through an ADFS proxy server. Last week, it stopped working completely returning an error of Service Unavailable 503 Error.

 

I have removed and reinstalled the Remote access server roll, and it always says ADFS proxy service is configured correctly.

 

There do not appear to be any errors in the Remote Access roll logs.

 

Not sure what else to look at.

 

This is on Server 2012 R2.