I tried to ask support of manufacturers, but it didn’t help. maybe someone here can help
Important note: I already connected this device to server (chirpstack) before, but after some downlink (i even don’t know why this downlink was sent) gateway stopped receiving frames
The actual model number of gateway and device would help substantially.
Blocking out the EUI’s is pointless and stops up checking online for status. You SHOULD have blocked out your “Secret Key”.
Settings for two frequencies in the gateway and a Tx & Rx frequency entry for the device raise suspicions that these aren’t really very compliant. There should be at least three, if not eight frequencies setup for the gateway.
But as you say, should actually show something in the gateway.
If Chirpstack sent a downlink, was it a Join Accept? Which may have changed the frequencies in a way that stopped the unknown device from working.