Error adding Identity Source

I am using the vCSA and I have joined it to the domain, and rebooted. I now am trying to add the identity source with "Use Machine Account" Windows Integrated Authentication. But I am getting an error that says "Check the network settings and make sure you have network access to the identity source". This is onsite and I can ping it by name and by IP. Any ideas of things I can try to fix?

Thanks for your time.