Outlook RPC over HTTP - not working

Hi there,

Whilst migrating from Exchange 2010 to Exchange 2013 I'm having issues with Outlook Anywhere (RPC over HTTP(s)).

In outlook 2013, setting up a new profile, the error says "the action cannot be completed. The connection to microsoft exchange is unavailable. Outlook must be online or connected to complete this action".

When Ok is clicked, I then get a prompt with ea86035d-4655-4cb5-9224-ebdc30221eae@publicdomain.co.uk and =SMTP:test.user@publicdomain.co.uk.

Using the Outlook Anywhere (RPC over HTTP(s)) testexchangeconnectivity.com test, I get the following:

Attempting to ping RPC proxy publicdomain.co.uk.
 RPC Proxy can't be pinged.
 
Additional Details
 A Web exception occurred because an HTTP 555 - 555 response was received from IIS7.

I have uninstalled/restarted/installed the RPC over HTTP windows 2008 r2 server feature numerous times without any effect.

All exchange servers are 2008 R2.
Exchange 2010 co-existence with Exchange 2013 CU1.

All other tests on testexchangeconnectivity.com works including autodiscover and activesync.
Any help/assistance is greatly appreciated and I apologise if this is a repeat post however I've been unable to find anything on the HTTP 555 errors.

Kind Regards,

Mark.