The question here is, why did the setup work with one Mac (the old work laptop) and not with a different one (new work laptop) and is there anything I can re-configure or change so as to make it work with the new Mac?
The hardware:
- Personal laptop: MacBook Pro mid 2015
- New work laptop: MacBook Pro 2023, Apple M2 Max
- Old work laptop: MacBook Pro, I don't have it to establish exact model but it was top of the line in late 2020
- Two 4K monitors, one Dell and one Samsung (models not important as these are working fine, only USB devices are giving trouble).
- KVM: Level 1 Techs 4K KVM switch, 5 gigabit option (this model)
- Dock: CalDigit TS4 Dock (this model)
- USB Hub: Sabrent 4-port USB 3.0 hub with individual power switches
- Mouse: Microsoft ergonomic mouse
- Keyboard: WASD Code keyboard
The setup:
- Mouse connected to USB HID port on back of KVM
- USB Hub connected to USB data port on back of KVM
- Keyboard connected to USB Hub
- Personal laptop connected directly to PC2 ports on KVM with multiple individual cables (no dock) and working fine.
- KVM PC1 ports connected to Dock with two Thunderbolt/DisplayPort cables for monitors, plus USB A to USB 3 cable for peripherals. (Also a 3.5 mm audio cable but that is working fine.) Connected to any USB A port on back of Dock.
- Work laptop connected to Dock with a single Thunderbolt 4 cable.
This setup worked perfectly for the old work laptop and is the desired setup. But for the new one, it does not: neither the mouse nor the keyboard works at all.
After going through all the usual suspects, unplugging and replugging everything, rebooting, powering on and off the individual devices, I am completely certain this setup does not work with the new laptop, even though the exact same setup did work with the old laptop.
But much more interesting, I established some other connection setups that DO work:
KVM USB connected directly to new work laptop (instead of to Dock) using a USB A to C adapter, and with mouse, keyboard and hub connected to KVM as described above — works perfectly.
Dock connected to work laptop as usual, but with keyboard and/or mouse and/or USB hub connected directly to Dock (USB A ports) instead of to KVM — works perfectly.
All as above in desired setup, except KVM connected into a USB C data port of the Dock (via A to C adapter) instead of into a USB A port on Dock — this works perfectly if one of the FRONT USB C ports of the Dock is used, but not the back USB C data port.
3b. Also works if one of the Thunderbolt monitor ports in the back of the Dock is unplugged and used for USB A to C connection from KVM.
All as in the desired setup except the USB Hub taken out of the mix, with the keyboard connected directly to the USB data port on the back of the KVM and the mouse connected to the USB data port on the front of the KVM.
In other words the HID ports on the KVM do not work with the KVM connected to the Dock via USB A, and the USB Hub into KVM data port also doesn't work with KVM connected to the Dock via USB A; and also these same HID ports or USB Hub ports do not work if KVM is connected to Dock via the USB C data port on the BACK of the Dock.
(Reasons I don't like these working setups: For setup (1) the port placement on the work laptop make this impossible; I had to twist computer at a weird angle to test this setup at all. For (2) of course it doesn't allow me to switch between work and personal with the KVM. For (3) and (4) having cables coming out of the front of the dock or the KVM makes the setup look kludgy, and for (3b) I'd like to have both monitors remain connected. Since I often don't use the second monitor, for now I have disconnected from the Dock the second monitor cable and plugged the KVM USB connection into that port via A to C adapter, i.e. using setup 3b. But I still want to know WHY and would really love to get the desired setup working again with this new laptop.)
The above working setups in combination rule out any possibilities of bad ports or bad cables. The fact that the exact same setup worked with the old work laptop rules out the possibility that the setup just purely cannot work for USB architectural reasons.
So, what gives? Why does this setup not work with the new work laptop?
