Fixing "No USB C Signal" error, U2722DE (and other) monitors

PSA on a problem I solved after spending hours trying to figure it out

Short version: Not all USB-C cables are the same. If you replace the short (3 ft or less) cable that comes with the monitor and get this error, it is likely because you are using a standard USB-C cable which doesn't support DisplayPort Alt Mode which is how the monitors receive a video signal via USB-C.

TLDR version: 

I have a desktop and laptop connected to a U2722DE which is daisy chained with a DisplayPort cable to a 2nd U2722DE. I was excited to leverage the new monitors to be able to get rid of a laptop docking station, a large KVM switch, and numerous cables, and was frustrated when everything worked except for video from the laptop. I spent a long time reading forum posts about unplugging and resetting/restarting everything, downloaded new drivers, tried multiple wiring approaches, etc etc and couldn't figure out why I couldn't get video to come through the monitors even though audio did and even though my keyboard and mouse were working fine. The only way I could get video to show up was by using an HDMI cable, however the daisy chaining feature to support dual monitors doesn't work with an HDMI input.

Even though I didn't see it mentioned anywhere in the Dell user manual or online help or forum responses, I eventually figured out that the problem was just the longer USB-C to USC-C cable I used to connect my laptop to the monitor, since the included one was too short for my setup. As I understand how these monitors work, they require DisplayPort input for the 2 main DisplayPort and USB-C ports, which means that the USB-C cable needs to be the thicker type that supports what is called DisplayPort Alt Mode. Specifically, you need what's called either a USB-C 3.1 or Gen2 cable that supports 10Gbps transmission speeds. 

So, if you're trying to use a single monitor with a USB-C cable to minimize the number of cables and power cords you need and/or if you have a dual monitor setup, that seems to be most likely problem if you get a error message on the display about it not getting a USB-C signal. You can easily find the correct type of cable on Amazon or elsewhere if you search for those specs.

Hope this helps save someone else the time I lost figuring this out.