4 minute read


Late 2021 I switched jobs and had to return the monitors I had borrowed for my home office. I had previously been rocking a dual monitor setup with two Dell monitors (24” portrait and 27” landscape, 1080p and 1440p respectively). The actual models were P-something for the 24” and U-something for the 27”, but the beauty of this setup was that the 27” had support for DP MST meaning it was possible to daisy chain the 24”. For the uninitiated, daisy chaining means that you can forward the video signal from one monitor to another one (i.e. you don’t need to pull a cable from the second monitor to your computer). I could connect one DP cable to my desktop computer and one Thunderbolt cable to my laptop, and then switch seemlessly between the two computers simply by changing the input source on the main (27”) monitor.

Finding a new monitor setup

1440p + 1080p was an OK setup, but I really wanted to step it up a notch and have 4k + 1440p instead. I think I combed through the entire Internet for: 27” 4k monitors with DP MST / Daisy Chaining support, to no avail. When searching, I learned two things: (1) monitor manufactorers are useless at listing whether their monitors support daisy chaining or not and (2) most people (especially in retail) don’t even know what daisy chaining is. After two weeks of looking I started to accept that I was unlikely to find monitors satisfying my needs and by extension I started to widen my scope a bit. I created a poll in one of Sweden’s larger developer-Slacks and pitted dual-monitor vs. ultrawide against oneanother. The result was close, which was enough for me. I started looking at ultrawide monitors.

Here comes U4021QW

I soon realized that I had two requirements for my ultrawide monitor:

  1. It must have a KVM switch so I can connect my peripherals to the monitor and switch between desktop and laptop seemlessly.
  2. It must have high enough resolution to give a similar amount of pixels as having two monitors (4k + 1440p).

(Un?)fortunately there aren’t that many monitors to choose from. A quick search on PriceSpy, filtering for resolutions [5120x{2160,2880}, 6016x3384, 7680x4320] yielded only a handful of options. I narrowed my selection down to a couple of 40” variants (which I thought would be a sweet spot of size to resolution ratio). The choice was made easy, since the only monitor in stock was the Dell U4021QW.

Living with the U4021QW

To begin with, I was really happy with the monitor. With 1.25 scaling in Wayland (or 150% in Windows) the resolution is good and I don’t think I would want a larger monitor. It has decent built-in speakers. The color accuracy is reasonable, from what I can tell, but I don’t really do anything color critical. I do miss having a portrait monitor though… but I use my laptop as a portrait monitor and it does the trick for now.

The problems begin

My number one requirement for the monitor was the KVM switch. I want to have all my peripherals plugged into the monitor and the switch between my desktop and laptop by the press of a button. This worked (note the tense) great in the beginning, but after a couple of weeks of use I noticed that my mouse started lagging. At the beginning it was barely noticeable but it became worse and worse. I started troubleshooting but quickly reached the conclusion that it must be the built in USB-hub in the monitor that is the culprit.

The monitor also started to switch to the Thunderbolt connection (even if the laptop was turned off) when I was using my desktop. This would happen spontaneously and the monitor would turn black, show a message about No Thunderbolt connection and then remain black. I have to manually select the DP connection in order to get my desktop back on screen. (The problem is mitigated by simply unplugging the laptop altogether, but that is certainly not a solution.)

I have an ongoing support case with Dell and they are sending me a replacement screen. So far, they have been nothing but helpful and hopefully I have a bad unit and the new monitor will solve all my problems!

Maybe buy another monitor?!

After I bought my Dell monitor (or I overlooked it), LG has released their 40WP95C. LG has explicitly listed that the monitor supports daisy chaining and the monitor seems to be at least on par with the Dell monitor on all other specs. LG does not mention KVM anywhere in their product specification, but do list Auto Input Switch which might be the same thing.

Should my second Dell monitor not live up to my expectations, I intend to return it and give the LG monitor a go instead.

Read on?

An update can be found here.