On 12/28/19, I too had problems getting to the JupyterLab server. In both the Developers’ Getting Started instructions and the DLI Course materials sections for Instructions For Linux, I found the wrong zipfile specified for DLI course work. The two locations as of this date are:
https://developer.nvidia.com/embedded/learn/get-started-jetson-nano-devkit#write
Once I found this posting, burned dlinano_v1-0-0_image_20GB.zip rather than nv-jetson-nano-sd-card-image-r32.3.1.zip, gave up on the Firefox browser and used Chrome, and swapped out 3-4 different USB A to USB micro B cables to get one which was data-capable, I did get a dlinano login that accepted the dlinano password.
Suggestion: include minimal-cost data-capable USB cable and one jumper in the DevKit, as well as fixing the written file names/locations/links, to increase developer acceptance of the kit and get us started more quickly on the interesting stuff.