@bed Yes, approach it step by step. First check the RF connection witrh the simple examples, which are tricky too. Then try ABP join, since that does not need downlink messages. After that go for OTAA join. There is indeed a problem with DRl 0 in the official 1.17.3.b1 revision, see https://github.com/pycom/pycom-micropython-sigfox/commit/ae3a294c40026433dbdac3e08da788b2b4c4dfdb, but that should not affect here.
@jmarcelino I've tweaked the LoRa configs in every way I can think of. I get the same results when using data rate 4. I suppose the next step would be to examine if the packet (header + payload) is being created correctly through socket.send() however I know of no way to do that at the uPython command level. Any suggestions of next steps?