I have an S2120 8in1 LoRa weather station (868MHz) on TTN in unconfirmed mode (1N). It worked perfectly fine until I deleted the device in the old application and tried to add it to a new application. I cannot physically access the device, otherwise it would work for sure.
A few assumptions here about the firmware, that you used OTAA and using my Google magic I’ve determined it’s a Seeed device so it’s likely to be using their LoRa-E5 which is based on LoRaMAC-node which doesn’t have LinkCheck baked in as standard which means …
Next time migrate the session. Or pre-plan a road trip.