L1KVM: Display signal lost after switching back to computer

[_Nathan]

Hi All,

I’m having a weird issue with my new L1KVM (PAAG-E3132B).

I have a desktop Windows 10 machine and a Windows 10 laptop (with a WD20TB) being switched by the KVM.
Whenever I switch back to the Windows 10 desktop I do not get any display output.
I also do not get any display output when I then plug my monitor directly to the GPU.
To “fix” the issue I have to restart my desktop get the displays to work again.

I’ve had a quick search through the event log and I don’t see any errors or warnings.
I suspect this may be an issue where the dGPU is getting disabled when no displays are detected?
There’s also no output on the iGPU port on the mobo.

Desktop Config:
AMD 5900X
64GB DDR4
NVIDIA 2070 Super (Latest Driver)
3x DP → DP Cables

Laptop Config:
Dell Latitude 5430
Intel Iris Xe Graphics
Dell WD20TB (Thunderbolt 4 Dock)
2x DP → DP Cables

Displays:
3x Dell S2722QC (4K/60Hz)
Using a Displayport → HDMI cable for them from 4Cabling.

//Nathan

[_Nathan]

After some more testing:

Leaving 1 display plugged into the dGPU does negate this issue.
However, now I’m only switching 2 displays and not all 3

[wendell]

Crappy cables.

It’s counterintuitive but you can’t just test one cable at a time. Since the kvm tries to be invisible you’re working on cable pairs, not individual cables.

The dgou gives up eventually trying to negotiate through the interference.

You could also try ddu.