Bug 513843

Summary:	RDP client video seems to have lost horizontal sync
Product:	[Applications] krdc	Reporter:	Emmett Culley <lst_manage>
Component:	RDP	Assignee:	Urs Wolfer <uwolfer>
Status:	REPORTED ---
Severity:	normal	CC:	ctrlaltca, nicolas.fella
Priority:	NOR
Version First Reported In:	25.12.0
Target Milestone:	---
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Emmett Culley 2025-12-26 16:50:31 UTC

SUMMARY
RDP client video seems to hav lost horizontal sync.  All I see is the expected destop as slanted lines.

I see this with Remmina as well so it may not be a bug in the client.

The target is Fedora 43 KDE live, but I've seen the same when attemp[ting to connect to Almulinux KED images.

I configured the remote target for RDP connsctons via that KDE system settings remote desktop dialog. 

STEPS TO REPRODUCE
1. Run krdc and enter info to connect to remote machine (VM)

OBSERVED RESULT
When connected the expected desktop displays as slightly angeled colored lines.  It is exactly as an old CRT TV would appear if it lost  horizontal sync.

EXPECTED RESULT
I expect to see that desktop of the remote machine's logged in user.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma:  Fedora 43
KDE Plasma Version:  6.5.4
KDE Frameworks Version:  6.21.0
Qt Version: 6.10.1
Graphics platform: Wayland

ADDITIONAL INFORMATION
The above is the same for the target remote machine.

Comment 1 Emmett Culley 2025-12-26 17:25:26 UTC

I did some additional investigation and it occured to me it might be the RDP server's video resolution.

I had been connecting to the  VM via virt-manager while setting up the VM.  I had changed the window size, which changed the desktop size.  The display ended up with a non standard H to V ratio pixel resolution.

So I tried setting the screen resoluton via the systems settings display dialog by selecting a couple of different resolutions from the dropdown.  Unless I selected a resolution with "weird" ration, they all worked from the RDP client.

So this appears to be an issue with how RDP handels non-standard target screen resolutions.

Comment 2 Fabio 2025-12-29 09:08:10 UTC

This should probably be reported to the upstream freerdp library: https://github.com/FreeRDP/FreeRDP
I guess they will need some more info about the server and specific resolutions being used, tho.

Comment 3 Emmett Culley 2025-12-31 16:45:38 UTC

Reported to freeRdp on gitHub:

https://github.com/FreeRDP/FreeRDP/issues/12097