I just build my redox keyboard and I found a problem about the right hand side is not working when connecting via the TRRS cable
The soldering work looks pretty rough (practice on a throwaway project first). Probably one of the TRRS or MCU pins is not well connected. Get out a multimeter and do a continuity check of all the connections. It could also be misconfiguration of QMK, but make sure the basics (hardware connections) are right first.
This is my picture of my PCB
Im not familiar with the redox, but i see you got two unpopulated resistor footprints around the trrs connector.
Are you sure the resistors are optional?
I think this is the answer, there might be more issues with the state of the soldering but the build guide says it needs them (indicating they’re using i2c for split comms).
OP needs to add 2x 4.7kOhm resistors on one half of the keyboard.
This. I built the redox and you do need those resistors, but only on one side if I do not remember wrong
