How to use the Dell U3818DW USB-C connection for video. When I had my desktop PC, I would use the HDMI and Displayport connections, but when I recently upgraded to a Microsoft Surface Studio Laptop, the only port options I had built into the laptop were the new Thunderbolt 4, or USB 4 ports. Initially I purchased a USB-C Dual HDMI mini dock / hub adapter by J5. This worked OK. But then I realized my secondary Dell U3818DW monitor was only working at 30hz refresh. I noticed lag on my zoom meetings where it looked like I was moving in slow motion. I researched the problem, but couldn’t find clear solutions. My conclusion was to purchased an Apple Thunderbolt 3 cable (0.8m); the cables are short in length because of the high bandwidth going through the cable. Previously, I tried various USB-C cables, including an Apple USB-C cable that came with my Macbook Pro M1, but couldn’t get any of them to pass the video signal, until I tried the Apple Thunderbolt 3 cable. The refresh rate is now 60hz on my Dell U3818DW and my laptop screen is 120hz. I even tried to connect a 2nd Dell U3818DW monitor for a total of 2 external Dell U3818DW screens plus the internal laptop screen, and both external dell screens still ran at 60hz. I hope this info helps someone. Had I known about this solution, I could have saved a lot of unnecessary costs!