Problem with IFD

Hi All

I have an issue with a CRM 2016 IFD config where is seems to go to the wrong URL!

I have followed an online config for the IFD with ADFS

eg.

My CRM organisation should be accessed as   https://org.test.co.uk:444 but when I go to that address the system redirects me straight away to the addresshttps://test.co.uk............ and not http://auth2016.test.co.uk......  as I would expect

If I manually add in auth2016 in from of the address all works OK!

Any ideas where the setting is that does this redirect?

Thanks

Wayne