INFO: [down] the last 10 PULL_DATA were not ACKed, exiting application

Observed the log, encountered this message, I have to configure something else?

*** Beacon Packet Forwarder for Lora Gateway ***
Version: 4.0.1
*** Lora concentrator HAL library version info ***
Version: 5.0.1;
***
INFO: Little endian host
INFO: found global configuration file global_conf.json, parsing it
INFO: global_conf.json does contain a JSON object named SX1301_conf, parsing SX1301 parameters
INFO: lorawan_public 1, clksrc 1
INFO: no configuration for LBT
INFO: antenna_gain 0 dBi
INFO: no configuration for tx gain lut 12
INFO: no configuration for tx gain lut 13
INFO: no configuration for tx gain lut 14
INFO: no configuration for tx gain lut 15
INFO: Configuring TX LUT with 12 indexes
INFO: radio 0 enabled (type SX1257), center frequency 867500000, RSSI offset -166.000000, tx enabled 1, tx_notch_freq 0
INFO: radio 1 enabled (type SX1257), center frequency 868300000, RSSI offset -166.000000, tx enabled 0, tx_notch_freq 0
INFO: Lora multi-SF channel 0>  radio 1, IF -200000 Hz, 125 kHz bw, SF 7 to 12
INFO: Lora multi-SF channel 1>  radio 1, IF 0 Hz, 125 kHz bw, SF 7 to 12
INFO: Lora multi-SF channel 2>  radio 1, IF 200000 Hz, 125 kHz bw, SF 7 to 12
INFO: Lora multi-SF channel 3>  radio 0, IF -400000 Hz, 125 kHz bw, SF 7 to 12
INFO: Lora multi-SF channel 4>  radio 0, IF -200000 Hz, 125 kHz bw, SF 7 to 12
INFO: Lora multi-SF channel 5>  radio 0, IF 0 Hz, 125 kHz bw, SF 7 to 12
INFO: Lora multi-SF channel 6>  radio 0, IF 200000 Hz, 125 kHz bw, SF 7 to 12
INFO: Lora multi-SF channel 7>  radio 0, IF 400000 Hz, 125 kHz bw, SF 7 to 12
INFO: Lora standard channel 8 disabled
INFO: FSK channel 8 disabled
INFO: global_conf.json does contain a JSON object named gateway_conf, parsing gateway parameters
INFO: gateway MAC address is configured to 00004C3FD3493E0D
INFO: server hostname or IP address is configured to "ixorigue.ddns.net"
INFO: upstream port is configured to "1700"
INFO: downstream port is configured to "1700"
INFO: downstream keep-alive interval is configured to 10 seconds
INFO: statistics display interval is configured to 30 seconds
INFO: upstream PUSH_DATA time-out is configured to 100 ms
INFO: packets received with a valid CRC will be forwarded
INFO: packets received with a CRC error will NOT be forwarded
INFO: packets received with no CRC will NOT be forwarded
INFO: Reference latitude is configured to 0.000000 deg
INFO: Reference longitude is configured to 0.000000 deg
INFO: Reference altitude is configured to 0 meters
INFO: fake GPS is disabled
INFO: Auto-quit after 10 non-acknowledged PULL_DATA
INFO: UBX timegps control enabled
INFO: [main] concentrator started, packet can now be received

INFO: Disabling GPS mode for concentrator's counter...
INFO: host/sx1301 time offset=(1605094343s:131475µs) - drift=640106835µs
INFO: Enabling GPS mode for concentrator's counter.


##### 2020-11-11 11:32:55 GMT #####
### [UPSTREAM] ###
# RF packets received by concentrator: 0
# CRC_OK: 0.00%, CRC_FAIL: 0.00%, NO_CRC: 0.00%
# RF packets forwarded: 0 (0 bytes)
# PUSH_DATA datagrams sent: 0 (0 bytes)
# PUSH_DATA acknowledged: 0.00%
### [DOWNSTREAM] ###
# PULL_DATA sent: 3 (0.00% acknowledged)
# PULL_RESP(onse) datagrams received: 0 (0 bytes)
# RF packets sent to concentrator: 0 (0 bytes)
# TX errors: 0
# BEACON queued: 0
# BEACON sent so far: 0
# BEACON rejected: 0
### [JIT] ###
# SX1301 time (PPS): 2434936
src/jitqueue.c:448:jit_print_queue(): INFO: [jit] queue is empty
### [GPS] ###
# GPS sync is disabled
##### END #####

JSON up: {"stat":{"time":"2020-11-11 11:32:55 GMT","rxnb":0,"rxok":0,"rxfw":0,"ackr":0.0,"dwnb":0,"txnb":0}}

INFO: Disabling GPS mode for concentrator's counter...
INFO: host/sx1301 time offset=(1605094343s:130265µs) - drift=-1210µs
INFO: Enabling GPS mode for concentrator's counter.


##### 2020-11-11 11:33:25 GMT #####
### [UPSTREAM] ###
# RF packets received by concentrator: 0
# CRC_OK: 0.00%, CRC_FAIL: 0.00%, NO_CRC: 0.00%
# RF packets forwarded: 0 (0 bytes)
# PUSH_DATA datagrams sent: 1 (111 bytes)
# PUSH_DATA acknowledged: 0.00%
### [DOWNSTREAM] ###
# PULL_DATA sent: 3 (0.00% acknowledged)
# PULL_RESP(onse) datagrams received: 0 (0 bytes)
# RF packets sent to concentrator: 0 (0 bytes)
# TX errors: 0
# BEACON queued: 0
# BEACON sent so far: 0
# BEACON rejected: 0
### [JIT] ###
# SX1301 time (PPS): 62436601
src/jitqueue.c:448:jit_print_queue(): INFO: [jit] queue is empty
### [GPS] ###
# GPS sync is disabled
##### END #####

JSON up: {"stat":{"time":"2020-11-11 11:33:25 GMT","rxnb":0,"rxok":0,"rxfw":0,"ackr":0.0,"dwnb":0,"txnb":0}}

##### 2020-11-11 11:33:55 GMT #####
### [UPSTREAM] ###
# RF packets received by concentrator: 1
# CRC_OK: 0.00%, CRC_FAIL: 100.00%, NO_CRC: 0.00%
# RF packets forwarded: 0 (0 bytes)
# PUSH_DATA datagrams sent: 1 (111 bytes)
# PUSH_DATA acknowledged: 0.00%
### [DOWNSTREAM] ###
# PULL_DATA sent: 3 (0.00% acknowledged)
# PULL_RESP(onse) datagrams received: 0 (0 bytes)
# RF packets sent to concentrator: 0 (0 bytes)
# TX errors: 0
# BEACON queued: 0
# BEACON sent so far: 0
# BEACON rejected: 0
### [JIT] ###
# SX1301 time (PPS): 62436601
src/jitqueue.c:448:jit_print_queue(): INFO: [jit] queue is empty
### [GPS] ###
# GPS sync is disabled
##### END #####

JSON up: {"stat":{"time":"2020-11-11 11:33:55 GMT","rxnb":1,"rxok":0,"rxfw":0,"ackr":0.0,"dwnb":0,"txnb":0}}
**INFO: [down] the last 10 PULL_DATA were not ACKed, exiting application**

INFO: End of downstream thread

INFO: End of upstream thread

##### 2020-11-11 11:34:25 GMT #####
### [UPSTREAM] ###
# RF packets received by concentrator: 0
# CRC_OK: 0.00%, CRC_FAIL: 0.00%, NO_CRC: 0.00%
# RF packets forwarded: 0 (0 bytes)
# PUSH_DATA datagrams sent: 1 (111 bytes)
# PUSH_DATA acknowledged: 0.00%
### [DOWNSTREAM] ###
# PULL_DATA sent: 1 (0.00% acknowledged)
# PULL_RESP(onse) datagrams received: 0 (0 bytes)
# RF packets sent to concentrator: 0 (0 bytes)
# TX errors: 0
# BEACON queued: 0
# BEACON sent so far: 0
# BEACON rejected: 0
### [JIT] ###
# SX1301 time (PPS): 62436601
src/jitqueue.c:448:jit_print_queue(): INFO: [jit] queue is empty
### [GPS] ###
# GPS sync is disabled
##### END #####
INFO: concentrator stopped successfully
INFO: Exiting packet forwarder program

In my gateway-bridge received data via UDP but not send ACK to gateway.

Note this line in your log:

INFO: Auto-quit after 10 non-acknowledged PULL_DATA

There is a configuration option in the packet forwarder config for this:

{
  ...
  "gateway_conf": {
    ...
    "autoquit_threshold": 3
  }
}