Any chance that also allows you to see some debug logging of the device?
While getting in touch with the supplier, you may also want to ask for the payload format documentation (or even a decoder), which other users of that device have not provided in Axioma QALCOSONIC E3 with OTAA. Aside, in that same topic someone writes:
I don’t think that would change the OTAA Join Request message, hence I don’t think that applies to you.