Reply To: Loads of CRC errors

I was looking at the logs and i saw the following:

Nov 11 20:24:09 mtcdt user.info lora-network-server: Frame transmitted to 00:00:00:04 via GW (00:80:00:00:00:00:c4:c9 Chan LC1 127.0.0.1:35817)  Seq# 1f
Nov 11 20:24:09 mtcdt user.info lora-network-server: Check response size: 00000004 sf: 7 bw: 0 dur: 56 < tm: 66 wnd: 1
Nov 11 20:24:09 mtcdt user.info lora-network-server: TransmitQueue canIncreaseDuration 0 66 0
Nov 11 20:24:09 mtcdt user.info lora-network-server: Band: 1 Time off air: 6100 ms
Nov 11 20:24:09 mtcdt user.info lora-network-server: Transmit UDP message to Gateway 197 bytes
Nov 11 20:24:42 mtcdt user.info lora-network-server: Parsing 1 rx packets
Nov 11 20:24:42 mtcdt user.info lora-network-server: SeqNo: 00000001 PrevSeqNo: 00000008 Duplicate: no^M
Nov 11 20:24:42 mtcdt user.info lora-network-server: Addr: 00:00:00:04 MIC Check: passed
Nov 11 20:24:42 mtcdt user.info lora-network-server: Packet accepted from Node 00:00:00:04  GW 00:80:00:00:00:00:c4:c9  (127.0.0.1)  Seq# 1  ADR enabled SF7BW125
Nov 11 20:24:42 mtcdt user.info lora-network-server: Schedule TX Time on air: 56 ms
Nov 11 20:24:43 mtcdt user.info lora-network-server: Queue app data 7 bytes
Nov 11 20:24:43 mtcdt user.info lora-network-server: Scheduled 12 bytes payload
Nov 11 20:24:43 mtcdt user.info lora-network-server: Frame transmitted to 00:00:00:04 via GW (00:80:00:00:00:00:c4:c9 Chan LC1 127.0.0.1:35817)  Seq# 20
Nov 11 20:24:43 mtcdt user.info lora-network-server: Check response size: 00000004 sf: 7 bw: 0 dur: 56 < tm: 61 wnd: 1
Nov 11 20:24:43 mtcdt user.info lora-network-server: TransmitQueue canIncreaseDuration 0 61 0
Nov 11 20:24:43 mtcdt user.info lora-network-server: Band: 1 Time off air: 5600 ms
Nov 11 20:24:43 mtcdt user.info lora-network-server: Transmit UDP message to Gateway 190 bytes
Nov 11 20:25:02 mtcdt user.info lora-network-server: Parsing 1 rx packets
Nov 11 20:25:02 mtcdt user.warn lora-network-server: Recv'd frame failed CRC check
Nov 11 20:25:10 mtcdt user.info lora-network-server: Parsing 1 rx packets
Nov 11 20:25:10 mtcdt user.info lora-network-server: SeqNo: bee27ba0 PrevSeqNo: 00000001 Duplicate: yes^M
Nov 11 20:25:10 mtcdt user.info lora-network-server: Addr: 00:00:00:04 MIC Check: passed
Nov 11 20:25:10 mtcdt user.info lora-network-server: Duplicate Packet accepted from Node 00:00:00:04  GW 00:80:00:00:00:00:c4:c9  (127.0.0.1)  Seq# 1  ADR enabled SF7BW125
Nov 11 20:25:10 mtcdt user.info lora-network-server: Schedule TX Time on air: 56 ms
Nov 11 20:25:11 mtcdt user.info lora-network-server: Frame transmitted to 00:00:00:04 via GW (00:80:00:00:00:00:c4:c9 Chan LC3 127.0.0.1:35817)  Seq# 21
Nov 11 20:25:11 mtcdt user.info lora-network-server: Band: 1 Time off air: 4100 ms
Nov 11 20:25:11 mtcdt user.info lora-network-server: Transmit UDP message to Gateway 166 bytes
Nov 11 20:26:59 mtcdt user.info lora-network-server: Parsing 1 rx packets
Nov 11 20:26:59 mtcdt user.info lora-network-server: SeqNo: bee27ba0 PrevSeqNo: 00000001 Duplicate: yes^M
Nov 11 20:26:59 mtcdt user.info lora-network-server: Addr: 00:00:00:04 MIC Check: passed
Nov 11 20:26:59 mtcdt user.info lora-network-server: Duplicate Packet accepted from Node 00:00:00:04  GW 00:80:00:00:00:00:c4:c9  (127.0.0.1)  Seq# 1  ADR enabled SF7BW125
Nov 11 20:26:59 mtcdt user.info lora-network-server: Schedule TX Time on air: 56 ms
Nov 11 20:26:59 mtcdt user.info lora-network-server: Frame transmitted to 00:00:00:04 via GW (00:80:00:00:00:00:c4:c9 Chan LC3 127.0.0.1:35817)  Seq# 22
Nov 11 20:26:59 mtcdt user.info lora-network-server: Band: 1 Time off air: 4100 ms
Nov 11 20:26:59 mtcdt user.info lora-network-server: Transmit UDP message to Gateway 166 bytes

The first time it sent the data, downlink worked. The next two times it didn’t.
Started saying “Duplicate: yes” . Why and how does it mark it as duplicate?
Why does it stop working suddenly like this.