You need to change a setting in windows for remmina to work. I don't remember which one it was but I think it was some where in the remotedesktop settings.
Have you tried gnome connections? It's more on the "quick and easy" rather than "professional" side, but maybe it does the job.
Tho I wonder whether it's more of a windows-side issue... maybe windows 11 requires some kind of online authentication that cannot be implemented by other clients, and maybe this authentication can be turned off. I'm merely speculating here, but I know that remmina works for windows 10 so it's suspicious.