Don't ask me why, but I've found lowering the color depth can help with remmina failing to connect.

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From: Richard Klein via WLUG <wlug@lists.wlug.org>
Sent: Friday, April 24, 2020 8:45:37 PM
To: Worcester Linux Users' Group General Discussion <wlug@lists.wlug.org>
Cc: Richard Klein <rich@richardklein.org>
Subject: [EXT] [WLUG] RDP into Win10 with Remmina
 
I'm getting tired of booting into Windows for work.  I figured out how to connect to the VPN from Debian, but it would be very helpful to RDP into the workstation in my office.

I know the URL for my workstation, the domain, the username, and the password, but I'm failing to get it to work.  What should I try?

Remmina says "Connecting to <server>..." for a minute, then fails with "Connection to RDP server <server> failed."

--
Rich