@freynder it is different. I don't know if they try to connect to each other and if some having issues with that it drains the battery.

Maybe off-topic, but those that don't know about Finite State Machines could have a look at these links for a start... https://en.wikipedia.org/wiki/Event-driven_finite-state_machine https://gamedevelopment.tutsplus.com/tutorials/finite-state-machines-theory-and-implementation--gamedev-11867

Thank you all. I changed the register values directly in the RFM69 driver and it all seems to work. Hopefully a new release will soon include this (as well as the ATC feature). Also, local legislation specifies maximum transmission power as 10mW for the 433 band, so I included the code below in my sketch. It would be good to be able to configure this in the future as well. #ifdef MY_IS_RFM69HW _radio.setPowerLevel(16); // 10dBm for RFM69HW #else _radio.setPowerLevel(28); // 10dBm for RFM69W #endif