KVM Model:
4 Ports 8k DisplayPort KVM switch
USB Interface (5-gigabit or 10-gigbit):
5-gigabit
Problem:
Challenging connection 1: Threadripper pro workstation with a 7900 xtx GPU. The cables used are a 5m fibbr display port 2.1 cable and a 5m cable matters super USB cable (blue color plugs).
OS: Rocky 9
Connected to port 3.
Green light is lit, and a red tint when I select the port.
When I have the USB cable plugged in my 4k monitor shows up as max 2048x1080 resolution with no signal going to my monitor. If I unplug the USB cable I can select the full 4k resolution, but still no signal going to the monitor.
I’ve tried to swap to ports 2 and ports 4 with the same result.
The keyboard and mouse work fine via the KVM.
Challinging connection 2: Port 2 is connected to an Anker dock for my work laptop. Laptop is connected via USB-C to the dock. Standard Dell setup.
The connection is a 3m fibbr displayport 2.1 cable and 3m cable matters super USB cable (blue plug)
When I switch to port 2 I get the “dell beeps” a number of times and then the displayport doesn’t connect. Keyboard and mouse work fine.
As opposed to my workstation no 2nd display shows up for this port.
Port 1 is connected to my gaming desktop, which works fine.
Same setup as port 2, 3m fibbr displayport 2.1 cable and 3m cable matters super USB cable (blue plug)
I’ve tried unconnecting all cables and the power supply for ~30seconds with no change in behavior.
Other Notes:
Corsair mechanical keyboard connected to the USB3 port on the backside with 1 cable and the (keyboard hub) cable connect to one of the HID ports.
Logitech 920 Webcam connected to the front USB3 port.
All the peripherals work fine.
Are you referring to this KVM?
What monitor?
Have you tried power cycling your KVM? By that I mean letting it sit for several minutes so the capacitors and efuse reset. 30 seconds, perhaps surprisingly, isn’t long enough to actually reset the KVM.
I believe its this kvm:
“1.4 Display Port KVM Switch - Single Monitor - Four Computer”
On the box the code, if I found the right one, is PAAG-E3114B with a dot in the US power supply.
Let me give the longer power cycle a roll. I’ll also disconnect all the cables in case there is a power path from e.g. USB into the KVM.
The monitor is on old Dell U3219Q.
For my workstation I have another monitor of the same type connected so I can see whats going on 
When I shift the KVM to the workstation and go to display settings the monitor is correctly detected as a 'Dell 32" 's monitor, the resolutions are off and the Dell monitor shows “no DP signal detected”.
The USB port in my workstation is a 10G port… mainly because thats all there is on the backplate for USB-A type connectors. I assume it doesn’t matter.
I tried the power cycle experiment.
- Disconnected power, unconnected all cables.
- Let it sit for 10 minutes to ensure full discharge of any caps.
- Reconnect cables
- Power on KVM.
The behavior is unchanged for the workstation in port 3.
For the workstation in port 3 the monitor shows “no DP signal detected” and the workstation display settings indicate a Dell 32" monitor detected and the resolutions are off.
For my work laptop connection in port 2 I found root caused the issue to be a ID10T error. Aka I had not connected the display port cable… instead I’d plugged in a fibbr HDMI cable… yes I’m waiting for the 4 port HDMI KVM to get back in stock
With the display port cable connected I can easily switch between my gaming desktop and work laptop, yeah
I did not shut down my gaming desktop nor did I turn off my monitor. Meaning they where powered connections when plugging out/in.
So now its just the workstation. I’ve run dual display with the GPU before using HDMI+DisplayPort. So that should be fine.
I’m guessing a next experiment is to try and use one of the 3meter fibbr display port cables instead of the 5meter cable? In case its a cable defect?
This is the cable btw: “FIBBR Certified Fiber Optic DisplayPort 2.1 Cable,DP2.1 Cable 40Gbps Video Display Port Cord Supports 16K@30Hz, 10K@30Hz, 8K@60Hz, 4K@165Hz, HDR, HDCP 2.2, 3D, ARC (16.4FT/5M)”
I tried the experiment with using one of the 3m fibbr cables instead of the 5m one and everything works fine. I would hazard a guess its a bad cable? I’ll get a replacement and see how that goes.
The only funk I’ve seen is the USB link wonking out and my usb keyboard/mouse began “rebooting”. A quick power cycle of the kvm resolved this.
Got my replacement 5m fibbr cable aaand everything is functional, yeah
Lesson learned… when you get a fibbr delivery from Amazon without shrink wrap its a recycled return 
Now I can get to swapping rocky 9 out with popOS… and wait with baited breath until the 4 port HDMI KVM is back in stock
@Level1_Amber issue has been resolved.
Visual problems are almost always cable quality related… I once had a used cutting board sent to me “new” from Amazon. Sorry for the lack of replies, I’m glad you were able to figure it out!