I've had trouble accessing Ubuntu over Gnome RDP sharing, except from a Windows machine. I can access Windows machines via RDP using e.g. Remmina, but accessing an Ubuntu host only seems to work for me from Windows regardless of the client I use.
Like, what client running on Ubuntu though? Remmina? I don't mean the RDP server setup, which is pretty self explanatory in settings. I weirdly can't make Ubuntu --> Ubuntu work, but with either host or client as a Windows machine I have no problem.