I basically followed this guide that I found after Googling the best way to change domain names on Server 2012. Now, though, when I look at RDS, the users that have access to a collection are in the format of "olddomain\domain users" and when I try to add users from the new domain, RDS tells me that the domain either doesn't exist or cannot be found.
This is a stand-alone server hosting AD, DNS, RDS, nothing else and it's the only server in the domain, though I could stand up another virtual if it's called for. Performing NSLOOKUP shows all the right SRV records, and none for the olddomain.
What I tried to do: I tried adding a new RemoteApp collection in RDS and assigning "domain users" to it.
Expected behavior: The users would add and the collection would publish.
Actual behavior: The user group that defaulted was "olddomain\domain users". When I removed that group and tried adding "newdomain\domain users", an error message popped up indicating the domain either doesn't exist or cannot be found.