I have see this on two different M1 Mac minis. The four Thunderbolt 3 ports on the 2018 Mac mini have been replaced with two Thunderbolt 4 ports. Theoretically that would be okay as the Thunderbolt 4 standard requires Thunderbolt 4, like Thunderbolt 3, can be daisy chained and unlike TB3 it can also be distributed like USB 2, 3.0, and 3.1 and is supposedly backward compatible. The reality I am encountering is…
  • I can't find any certified Thunderbolt 4 cables or hubs (a phone call to OWC indicates they may have some shipping by mid-December)
  • Connecting the TB4 port on an M1 device to a TB3 port using TB3 cable the connection stops at the first connected device and does not daisy chain.
  • The same connected devices using the same ports and cables daisy chain correctly if the first device is a TB3 port on an 2018 Mac mini.
  • Thunderbolt 2, 3, and 4 connectors are active with sophisticated electronic circuitry and hardware.
  • OWC's TB4 cables are limited to 0.8M (29 inches) and expectations are all TB4 cables will be costly.

My question is will the TB4 daisy chain always terminate at the first non-TB4 device?


If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein