@novicit Could you share schematic and software of your node?

@tekka In my case there were two problems. First same as @Mark-Swift, bootloader deley. I didn't expect that it takes about 30 seconds. Second one was that my gateway didn't run. In this case bootloader is still running and serial output isn't provided.

I have same problem as @n1ck1355. Shetch upload works, data are send, but serial output doesn't work.