please help :(

Level1 Store KVM Helpdesk
1

hi all,

first and foremost, I am not a tech person , at alllll. The only reason why I know what a KVM is is thanks to google when I asked how to share a monitor between two laptops. I dont know the actual difference between display port and hdmi, just that they look different.. now onto my issue.

I now have 4 laptops (two HP, one thinkpad, and one yoga) and one wide monitor (Samsung S34J55W). I don’t game and really only live in Microsoft Excel or Google Sheets. I am desperately seeking a KVM that will work with my setup. I run one keyboard and each laptop has its own mouse. The laptops have a USB Type C adapter plugged in to accommodate the HDMI cable, the keyboard cable (the square guy to the KVM), and the bluetooth mouse usb dongle. The cables run about 3 across my desk

I originally purchased a Startech 4-port HDMI USB 3.0 KVM in 2023 and really liked it - until it started blacking out two of my laptops frequently. I figured it could have been bad HDMI cables and ordered new ones. It did not solve the issue. Their helpdesk had me turn down the refresh rates to nearly 30Hz and it did not really improve the situation. I decided to try a TESmart HKS401-M24 and it is flickering across 3 laptops, constantly adjusting the laptop displays when I switch from input 1 to input 2 and 3 and so on. I tried contacting their helpdesk and they said what I was describing simply couldn’t be happening. It’s even worse now because the monitor will change to 1920x1080 display randomly and makes my monitor practically unusable. I have to play with the 1-4 display buttons a few times before it decides to act right.

So here I am, begging for help and not understanding these devices which are not cheap, but willing to invest in something that just works flawlessly. Again, I just need excel and email to work. I don’t do video work and I don’t even go on youtube, which I feel is the bare minimum these KVMs should be able to handle.

Am I completely out of my mind? Or is there something from LevelOneTechs that can certainly remedy these flickering issues I keep having?

Thank you

2

LevelOneTechs do offer KVMs, and some are in stock. My mother has a 2 computer, 2 monitor from here without issue, and I use a 2 computer 3 monitor one myself. I use a USBC-DisplayPort splitter for the work laptop, but otherwise its great.

3

Can you list what cables you’re using at the moment and if anything is near your current KVM?

Flashing black screens usually mean there’s a bandwidth issue or interference. Bandwidth issues usually stem from lower-quality cables or cables that are too long.

You could try attaching a ferrite clamp to your current troublesome connections:

4

These are devices with their own electronics inside to generate the video signal for the monitor or kvm. Personally i am suspicious of these dongles having issues, since you are having issues with two kvms of a decent brand and already swapped the cables.

5

A lot of USBC to HDMI are only 4K 60 as well.

If we plug in the Samsung S34J55W info into our bandwidth calculator, we get this:

Screenshot from 2026-04-14 15-48-54
Screenshot from 2026-04-14 15-48-54987×1025 93.3 KB

I wonder if USBC → HDMI cable is lowering the bandwidth