Early firmware builds (like version 8.1) suffer from severe audio buffering and stuttering when the player is in your pocket. Versions 8.3 through 9.21 drastically stabilize bidirectional Bluetooth connections.
This is often the most challenging part, as F.Audio does not host firmware files on a central, easily accessible website. Owners have reported that the best places to find firmware are: faudio fa4 firmware upd
F.Audio FA4 Firmware Update: The Complete Guide to Optimization Early firmware builds (like version 8
The device will restart and install the update. Do not turn off the player during this process. faudio fa4 firmware upd