Return to join

[imasd]

I'm working with a fipy, with communication by LoRa. MY fipy communicates with a Multitech Conduit gateway. Makes join and send data perfectly. My problem is that if they stop communicating (unplugging the gateway), I can not get them to join again later.
I was able to reestablish the join, rerunning lora.join() after getting a LoRa.TX_FAILED_EVENT, but it gives me 'OSError: the requested operation failed' and the lora.callback() function stops running.
So, how can I reset a join after a connection failure? Thank you