You’re right about the wiring; if you see packets then that’s probably okay.
Please make sure you got the terminology right. As you’re referring to a Join Request, I assumed this is an OTAA node. A Join Request uses the DevEUI, not a Device Address (DevAddr, which is calculated from a Join Accept).
If you’re looking in the local gateway log (rather than TTN Console) then I guess you compared with a node that does work, so I guess you know how to decipher the log then. But just to be sure: beware that many details are in reverse order in a LoRaWAN packet. (You could use an online decoder when unsure.)
If you’re seeing a Join Request with the wrong DevEUI in the Gateway Traffic in TTN Console (see No Join Response from TTN for expected screenshots of gateway and application), then the node must be configured wrongly.