I’ve been struggling to find a way of connecting my SurfaceBook 2, running Debian, to two 4K monitors at the same time.
I have tried lots of docks which did not work, to the point where I had almost given up.
But I decided to give it one last try and, finally, I have found something which does work, mainly thanks to the very kind assistance of Iain Wallace in the fediverse, who put me on the right track:
so a usb-c (not Thunderbolt) dongle that has two display outs and supports two displays will probably work for you (MST normally fine in linux). Cheaper than the sonnet dock, not all support two displays mind. Look for something that says it doesn’t support two displays on mac only PC (as macs can’t do MST so that means it uses MST for the displays).
The clue was “MST”.
I bought the StarTech.com USB-C to Dual HDMI MST HUB and it only worked straight away!
So now I have this hub connected to the one USB-C port of the SurfaceBook 2, which means I have to use Microsoft’s own odd connector to power the machine. But that’s fine - it works, and I had a dock which uses the Surface connector anyway, thanks to my myriad attempts to get two monitors working.
The screens only run at 30Hz, but (a) it works, and (b) that doesn’t really bother me.