Ever since I installed all the relevant firmware/driver updates for my TB15 and XPS-15, I have experienced random BSOD's. I finally have narrowed the cause down to the driver for the Realtek GbE Family Controller. That driver is rtux64w10.sys. I have installed the latest version (10.6.1211.2015) from the Dell Support site. I was using a previous version (10.5.1019.2015) with another USB-C Ethernet adapter and that worked fine. This is one among several problems reported here about the TB15. If this is not fixed shortly, I will be forced to return it.
I ended up returning the dock and uninstalling all related software. Realtek has newer drivers available - v10.10 vs v10.6 (which is the latest on Dell's site from last February). If you can get someone from Dell to verify that you can use the drivers directly from Realtek and that the proper device ID for the Ethernet controller is RTL8153 (I believe this is what it is), you can try that. Otherwise you are out of luck until Dell does something about the several driver issues that are associated with the TB15.