I'm using an Arduino Uno as a kind of wrapper for my WS2812B. It receives brightness values for each LED via SoftwareSerial and outputs them to the LED Strip. With a Strip of 53 LEDs and each getting a new value (1 byte) ~43x per Second it worked fine with a 38400 baudrate on the SoftwareSerial.
Now I enahnced it to a Strip of 107 LEDs and it stopped working. Even when all inputs should be 0, there are still some LEDs randomly lighting up (Problem A) and when I for example make the input so that only the first few LEDs should light up, then they are randomly (and fastly changing) lighting up all over the place (Problem B)
Changing to 57600 baud made Problem A worse, but changing to 115200 baud mostly fixed Problem A, but no luck with Problem B.
I'm not good with runtimes and so on, but is the Uno maybe too slow to receive those values and write them to the LED strip?