Hey all, @wendell was kind enough to consult with me over email and I’m reporting back findings here. It looks the Moshi DisplayPort/usbc cable is working perfectly where the Club3D wasn’t cutting it. So here are my findings for getting the L1 KVM to work with 3 displays on a MacBook 2023 M2 Max (the only Apple Silicon MacBook that works with 3-4 displays):
Displays 1-2 (through dock):
28MQ780-B =>
L1 KVM =>
TBT4-UDZ Dock =>
MacBook
Displays 1-2 going through the dock don’t seem to be as picky about cables. I used a mix of Club3D cables and whatever came with hardware.
Display 3 (direct to laptop):
28MQ780-B => (via FIBBR 6.6FT fiber optic DisplayPort Cable)
L1 KVM => (via Moshi DisplayPort to USB-C Cable)
MacBook
After 1.5 days of testing I’ve had no dropouts, the display has survived sleep/wakeup ~5 times, and I have no visible signal noise. Seems to be working great.
Note that I went back and replaced the FIBBR cable with my old DisplayPort cable and that didn’t work, so it’s BOTH the FIBBR and Moshi cables that are necessary for this to work for me for whatever reason.