XPS TB 16 Internet/Ethernet Issue

I'm really stumped! I have an XPS 13 (9360) and a TB 16 Dock.  When I'm plugged into the Dock, my tray shows that I have an ethernet connection but I can't access any websites.  I'm able to use my WiFi connection without any problems and even more confusing is the fact that when I unplug the ethernet cable from the Dock and plug it directly into my USB-C port (with an adapter) everything works fine. (So as best as I can tell there's no modem or router issue)   I've assumed the problem to be with the Dock and have reinstalled the firmware and all drivers, but with no effect.  I've run out of ideas and would really appreciate any guidance from anyone who may have some thoughts....

Thank you.