Thanks for reaching out to us, I am sorry this is not working as expected and I am happy to help!
The UD-6950 USB 3 Dual 4K DisplayPort Docking Station should be compatible with the Dell U3818DW (https://www.dell.com/en-us/work/shop/dell-ultrasharp-38-curved-monitor-u3818dw/apd/210-amrc) at 3840x1600 resolution based on the specifications.
Our first step is to make sure the DisplayLink software installed on the system is the latest recommended version and that we have removed any traces of older DisplayLink software that may have been installed through Windows Update or from Previous installations:
** Future readers please note, these instructions are updated as of March of 2020, as new drivers and software utilities are released these links will not be updated and may lead to installing older software. **
- Disconnect the dock from the system and please remove the power cable from the dock so it turns off completely (this is important so the unit resets). Please also disconnect the 1440x900 display from the system. Please keep these disconnected until the last step.
- Uninstall any and all software with ‘DisplayLink’ in the title that is present from within the Control Panel -> Programs and Features. Don’t worry if these entries are not present or if the process does not work, just move onto the next step
- Download and run the DisplayLink Installation Cleaner utility, found here --> https://s3.amazonaws.com/plugable/bin/DisplayLink/DisplayLink+Installation+Cleaner+9.1.1462.exe and ensure it displays “Cleaning Complete” when done (video walk-through if you need it -> https://youtu.be/AcVV1gD_FvI)
- Once the Cleaner has been run, reboot (even if not prompted to)
- Now download and install the 9.2 M3 DisplayLink software, found here --> https://plugable.s3.amazonaws.com/bin/DisplayLink/DisplayLink+USB+Graphics+Software+for+Windows+9.2+M3.exe
- Reattach the power cable to the dock first. Once the dock is powered on, reconnect it to your system. If the device is not detected, please reboot the system.
Please let us know if that helps get things working how they should, and we’ll go from there.