I have recently setup a RDS implementation on Server 2019, an upgrade over my old Server 2012 R2 RDS setup, it works perfectly for windows systems using the Web Access Portal (the IIS web page).
Mac users though have to use the Microsoft Remote Desktop App. This used to work fine in the Server 2012 R2 RDS environment with this behavior-
Remote feed setup for Microsoft Remote Desktop 8 - https://remote.domainhere.org/rdweb/feed/webfeed.aspx
Remote feed setup for Microsoft Remote Desktop 10 - https://remote.domainhere.org
Now on 2019 Microsoft Remote Desktop 8 will not connect at all, and some users get in fine with 10 using the address mentioned (https://remote.domainhere.org)... but a bunch of users when entering this string get this error: no workspace is associated with this url
If I configure a gateway pointing to our gateway address and a PC behind the gateway they can connect using the "PC" tab just fine, and if they go through Chrome to the Web Access Portal and download an RDP file for a connection to any Session Host those RDP files can be loaded into the Microsoft Remote Desktop app without issue...
I've had users uninstall the app, delete all the library settings for it, restart, reinstall the app and still no behavior change occurs.
Some possibly relevant information: This seems to be users who first loaded RDP files from Chrome before trying to configure the connection string for the Workspace (But I haven't confirmed that this is the case for all of these users)
If I edit the saved connection information loaded from one of these Chrome downloaded RDP files, either in the RDP file or in the Microsoft Remote Desktop app the app ignores the changes and connects to whatever the RDP file originally specified (really weird, it's like it's saving this info somewhere the user can't see and manual edits are not taking effect.
I've tried disabling the firewall in MacOS for these users (but they were all able to connect to the old environment fine and can connect directly to systems as described above so this doesn't sound like a firewall issue to me)
The RDS Environment is configured to use the Azure AD Application Proxy (in passthrough mode, since pre-auth isn't compatible with the Microsoft Remote Desktop App).