MQTT : How to Retain Sonoff Switch Setting across Restarts of HA

Configuration
19

Found it…

user_config.h (MQTT_POWER_RETAIN) :

#define MQTT_BUTTON_RETAIN     0                 // [ButtonRetain] Button may send retain flag (0 = off, 1 = on)
#define MQTT_POWER_RETAIN      1                 // [PowerRetain] Power status message may send retain flag (0 = off, 1 = on)
#define MQTT_SWITCH_RETAIN     0                 // [SwitchRetain] Switch may send retain flag (0 = off, 1 = on)