RDS 2012 Certificates – Subject Names do not match

I'm evaluating RDS on 2012, I want to use Remote App to allow home workers to access one application

This is a single server setup at the moment

Server Name acmeVDI.acme.co.uk – This has RD Web Access, RD Gateway, RD Licensing, RD Connection Broker and RD Session Host installed and configured from the Evalusation download

I have invested in a certificate from VeriSign for the trial, FQDN of this is vdi.acme.co.uk with a subject alternative name of acmevdi.acme.co.uk The certificate all checks out in the Manage Certificates area, all four entries are using the same Certificate

This works perfectly within my network, I can connect via the Remote App and Desktop Connections control panel item and can also connect internally via the Web Interface with a url of https://vdi.acme.co.uk/rdweb/

Externally, I can connect to the web interface using the same URL, https://vdi.acme.co.uk/RDWeb/ … but…

I can then enter my username and password, my list of published applications appears and I can then click on the app I want to launch.

I'm prompted to open Open or Download the RDP file, I select Open

I then see the "Do you trust the publisher of this remote connection", I say Connect

The normal RemoteApp Starting screen appears with the name of My App shown, after a few seconds I get an error message titled "Remote Desktop Disconnected"

The message then reads "The computer can't connect to the remote computer because the certificate authority that generated the Terminal Services Gateway server's certificate is not valid. Contact your network administrator for assistance"

There is a View Certificate button, which shows my Verisign certificate is valid and the certification path is also valid

Firewall is configured to NAT off HTTP and HTTPS traffic…and this is working to get this far

I think I'm so close, but what ever I try I get no success at this point connecting remotely, the remote PC is not a domain PC and has never been.

What do I need to check next please

Thanks