Not sure what I am doing wrong, I tried many different sketches from 3rd parties on 2 different Arduino UNOs, but I always get the same problem; it takes hours before I get any data at all to show on TTN. I use ABP. When data appears it never stops, and every emission is working fine.
I tried OTAA as well, and with it I can at least see some action, but it also takes a very long time to join.
I have at least 3 gateways in the vicinity, none of them are mine.
Could well be essentially the same problem, only with re-use of the join nonce. In that case you would not see join accepts being generated until the node tries a join nonce it has not previously used.
Or it could be a node with flaky receive window timing, such that is usually fails to catch the downlink packet. In that case you would see join attempts being generated, the node would just be missing them.
Or you could have one of the notorious single-channel non-gateways, in which case most of the packets transmitted by your node would be getting lost (but it doesn’t sound like that, given you describe that it keeps working once it starts to)
It’s backwards ones and repeats that are rejected.
Ultimately the frame counter is 32 bits, with only the lower 16 bits transmitted, but all 32 covered by the cryptographic checksum. Practically that means there’s a range of gap where guessing if a jump in count incremented the high bits might be necessary, and then the guess (or guesses) are checked with the checksum. So ultimately skipping millions or billions of counts forward would fail but realistic forward skips from being out of range for a while at permissible packet rates are handled.