Since I upgraded to 12.04, I am unable to RDP to a Windows 7 server. All I can see is a pop-up that says "Uable to connect to RDP server ". I am able to RDP using Vinagre, so that rules out any issues with my router or the Windows server. As far as I can tell, there are no logs from Remmina and the Debug window shows a blank. Any one got any ideas? Thanks.
I had a similar problem, getting the "Unable to connect to RDP server" message using Remmina and Ubuntu 12.04 to a Windows 7 machine.
It worked fine for weeks and then suddenly stopped.
What fixed it was going to ~/.freerdp/certs and deleting the problem server from that file.
The next time it connected, it asked for a new cert and worked fine.
I have no idea why it worked, but I started changing settings one at a time. When I edited the connection properties, I looked on the "advanced" tab and changed the security from "negotiate" to "TLS", and voila, everything works.
Strangely, "negotiate" still works on the laptop, but at least I'm back in business with my bigger monitor :)
I haven't had any files in ~/.freerdp/certs/ so I went ahead and cleared the file ~/.freerdp/known_hosts with this command:
echo "" > ~/.freerdp/known_hosts
Be careful! This will erase the entire file. I only had one entry, so it was okay.
Afterwards connecting to the server Remmina asked me to accept the servers certificate, which I did, and everything was finally back to normal. I suspect that an update of Remmina or the RDP protocoll might be the issue.