My UNI FAN SL V2’s controller shows up as 6K7750 in the device manager.
  1. Please update the FW using the SL_V2A file.
  2. If the fans are uncontrollable, then use the SL_V2 file instead.
After Boot, Fans Revert to Rainbow and L-Connect 3 Loses Lighting & Speed Control – Requires Reboot

1.  First, confirm that L-Connect 3 is on the latest version.

2. Go to Settings > General and input “7s” in the blank box to delay service startup.
➡ If the issue persists, try 12s.
➡ If still unresolved, initiate RMA for the controller or pump block.

I have both 120mm and 140mm, the 140mm spins slower.

Set the fan size at the Fan/ Pump profile to the corresponding fan size to obtain accurate fan speed.