My port is advertised as "Thunderbolt 3/USB 3.2 Gen 1 Type-C port with DisplayPort with alt mode". I guess the problem is that it can't speak whatever version the cable understands? The cable says "thunderbolt 3 compatible". And like I said, the same cable worked fine with the same monitor and a previous Dell laptop. :-/

That's crazy, I just got a new laptop from work, a lenovo instead of a dell, the dock is still an older dell thunderbolt dock, and it refuses to correctly work with the laptop. My (3) monitors show up but ethernet and usbs all cycle in and out. I kinda expected it bec the dock had a lot of problems even with dell laptops I eventually got it to work with mine but I know it got so bad dell stopped selling it pretty quickly. Now I need to shell out $400 to lenovo for a new dock that will (hopefully) support 3 monitors at 1080p60hz.

I feel like thunderbolt has gotten to the point that you could legitimately make a great side hustle on affiliate links from in-depth usb-c and thunderbolt accessory reviews.

That sucks - but I can attest that the Lenovo Thunderbolt dock is very solid (I have one of each generation).

That sounds like it should work, yeah. USB-C alternate modes should work over any TB3 cable (as far as I know). That's weird.

They won’t work over active thunderbolt 3 cables

Is that true? Hunh, I was unaware. So a TB3 dock with DisplayPort is handling the display protocol? Is there a standard driver on the OS side?

Not true, thunderbolt 3 can carry up to 8 DisplayPort lanes, something usb-c alternate mode cannot do. Both can coexist

Interesting - I must have misunderstood. Is there a good protocol breakdown of the USB-C to Thunderbolt changes and switch-over? (I assume there has to be, as USB4 brings them closer together?)