Duplicate Fcnt in uplink messages not filtered (OTAA)

chirpstack-network-server: 3.16.6
Device-profile : OTAA
Lorawan: 1.0.3

Hey all,

I have a gateway where sporadically duplicate fcnt are not filtered and are forwarded to the mqtt topic by the on-gateway network-server.
These are most likely most likely retransmissions as SNR/RSSI and timestamps are different.
Re-joining the sensor does not help

Is something I can do to reduce the problem ? I was considering deduplication_delay but this is only for multiple gateways and a single network server.

Are you using confirmed uplink?
There is no retransmission if using default unconfirmed uplink.

@datnus Actually even for unconfirmed there is retransmission. The NS server sends the LinkADReq MAC command with NbTtrans that tell the device to re-sent the same message more times.

However, these duplicate should be filteded

Do you have the skip frame-counter check enabled? In that case it could explain the duplicates. Note that changing this value becomes active after re-activating the device.

Thank you for replying.

The device is using a OTAA profile and I checked the skip frame-counter is disabled.

Do you have any other ideas how I could debug this ?