Hi all,
Should anyone face the same problem, I found the root cause: brownout threshold. I burned a new bootloader (Optiboot 8.0) without such trigger and the node has been working with used batteries (~2.7V) since May.
Hope this helps.
@Tommas Hi, now I've posted a device for sale on Tindie, if it's still relevant for you https://www.tindie.com/products/avikmen/usb-rf-gateway-with-stm32-and-nrf24-in-case/
