15 R3, 10Gb ethernet adapters

I've only ever seen 10 GbE external adapters with a Thunderbolt 3 interface.  I'm guessing that USB 3.1 Gen 2, though also technically rated for 10 Gb, would impose too much protocol overhead to allow anything close to 10 Gb worth of Ethernet traffic to cross through, so vendors may have decided that a 10 Gb Ethernet adapter that uses a more widely available interconnect isn't worth the support calls or bad reviews about poor performance.

I have however noticed that certain Thunderbolt 3 accessories like 10 Gb Ethernet adapters, TB3 to Dual DisplayPort adapters, and eGPU enclosures require a certain firmware level, and Dell has indeed been slow to deliver them on some systems, which is particularly frustrating given that updates are available for other systems that use the same TB3 controller chipset, though their update packages are not compatible with systems that don't receive those updates.  That said, the XPS 15 9550 spent quite a bit of time in this camp on NVM 12 or 13, and after a lot of complaints on this forum from owners who wanted to use a variety of those accessories with their systems, Dell did finally come through with an update to bring that system current.