I’ve been doing some testing with OTAA and come to face the same issue. In addition, this error seems to relate to the data rate and come to think of it, you were talking about this over in this post. Does anything you said over there have to do with what’s happening here?
When it says invalid_data_len, no transmission happens which means I can’t see the data rate we are talking about in the TTN console. I’ll see if I can find a way in the library to show what data rate we are on and then that might help.
I did find this post which states they can’t send more than 10 bytes, whereas I’m unable to send more than 11 bytes (24 with header). Their setup is very similar:
I have an RN2903 module (915Mhz) communicating with a network server.
Data rate : SF7BW125
Coding rate: 4/5
I am unsure about my data and coding rates, however considering I am about 10 metres from my gateway, I would think they would be similar. The only issue with this person’s post however is that there has not been a response, so it’s a dead end.
I have also found this post which talks about the limits of the RN2483 which he states is 191 bytes, however no answer is given here either.