The unit would lose signal to monitors quite often. You had to power off unit before it recognized any other monitors.

Does not work with multiple monitors daisy chained (MST). Incredibly annoying beeps when using the buttons.

My unit was also unreliable in a single monitor setup.

Very good box. The design is exactly what is expected.

Works fine but hate that beeper (needs an disable switch)

The failure rate of these devices are extremely high. I've accidentally bought two of these and RMA'd one. None of them have met my needs.
The best device I received would never turn on a monitor from a computer that went to sleep (I had to pull the power to restart the KVM to get it to work).
The others had problems switching to different PCs (1, wouldn't switch to another port if it wasn't occupied with cables. Another would just not switch in any case.
In efforts to future proof my setup, I've not found a single one of these devices to work correctly.
I have since switched to the two port, two monitor device that works as expected from the first unit recieved.

I have Dell tablet, via a display link dock and a Dell mirco connected to the switch. No issues from the switch. It swaps the monitors and keyboard as expected. The only issue I run into is when the micro hibernates. Once I start it again, sometime the mouse will not connect. I can solve this issue but removing and reinserting the dongle in the switch. Not sure if this is a switch issue, wireless mouse issue or Dell issue. Doesn't happen enough for me to investigate.So far less than once a month.
As other have mentioned, the beeping can get annoying. Other than that it works for me.

I'm returning this as it has become a major source of frustration due to being unreliable and poorly designed.

The only benefit to this switch is that G-Sync does work properly.

The main switching button on the front panel only works maybe half the time and the other half the time, I either get no video on the screen or no keyboard functionality. This is true no matter what computer I connect to it. I've got a MacBook Pro, a gaming PC, and an Ubuntu workstation. Switching to/from any of these results in the same issues where either the monitor receives no signal and then turns off, or the devices connected aren't recognized correctly.

The switching button is also really poorly designed. Even if it did switch on every button press, it is sequential, meaning you have to press the button and wait each time you want to switch the inputs, even if there is no computer connected--it doesn't automatically skip over a disconnected input.

This is especially bad when used with a laptop and docking station. The manufacturer might argue that this is not to be used with a laptop docking station, but with the MacBook Pro, there's no other way because DisplayPort somehow needs to come out of the USB C ports. I've tried two different docks for the MacBook, both of which work just fine when connected directly to the monitor.

Minor quip: the only cables that come with this is the power cable. Every USB and DisplayPort cable must be provided by the user.

When it works, it does it's job just fine and signals pass through just fine. But it is pretty terrible at it's main job, which is switching between computers. After a switch I often have the problem of the screen not being recognized by the system, peripherals not being recognized, it getting stuck on one of the 4 inputs (pushing the one "Select" button does nothing). After frantically unplugging and replugging cables at random and turning the unit off and on again, I usually can get it to work.
After the connected computer goes to sleep, the KVM will give out pretty loud beeps that will not stop. The bare bones manual does not mention anything about the beeping, let alone what the different beep patterns might mean or how to rectify the situation.
It's impressive how cheap this is compared to similar models, and you can forgive issues such as a bare bones construction, but it just doesn't do what it claims to do.

There pretty much isn't any other alternatives to this guy. There are lots of dual HDMI KVM's but nothing for DP unless you have a big wallet.

This KVM works well. I use it pretty much every day to switch two 4k displays between my work laptop and gaming desktop.

The only reason I'm deducting a star is because IT BEEPS ALL THE TIME. Seriously you're thinking how bad can the beeping be? Trust me it is bad!

If my laptop or desktop goes to sleep after not being used for a bit this thing starts beeping and it WILL NOT stop until you unplug it. At some point, I will have to open it and remove the beeper but I haven't had time yet.