I have been using my USBC Triple for a couple years now without any problems in multi-monitor setup. Last prime day, I bought the Dell U3818DW.
The monitor cuts out every 11-15 minutes with a signal loss/searching for signal. Takes about 5 seconds to sync back up. I do not see the green nor blue light on the plugable change and stay solid.
I have upgraded the Dell drives to the latest version and have also updated the Plugable to its latest.
I do not have the issue when I downgrade to a HDMI1.4 cable nor do I experience it with a USB-C cable - both plugged into the 4k port. I have also swapped out the HDMI cable with same intermittent signal loss.
Comp: Dell XPS 13 9380
OS: Windows 10 Pro
Dell U3818DW Firmware: M3B105
Os Drivers: 20 Jun 2017
Thank you so much for reaching out to us, I am sorry to hear that you are running into this issue, but I would be more than happy to assist!
Based on the description of the issue, and the fact that the cable change to an HDMI 1.4 does not experience the same issue, the problem may be related to the fact that the Dell display outputs at 60Hz natively via 3840 x 1600, which is not supported on the 4K HDMI port on the dock. If you downscale the resolution to 1920 x 1080, does the same issue occur?
Thank you so much for trying that out! This may be why you are running into this issue, as the highest refresh rate for the native resolution on that display supported on the dock should only be 30Hz, and disconnection issues can occur if the refresh rate is not within this range.
The TBT3-UDV does support 4K@60Hz via a direct DisplayPort to DisplayPort cable, or via the secondary Thunderbolt 3 port if your display supports Thunderbolt 3.
Please let me know if the same issue occurs when downscaling.