RN2903A based device does not join (OTAA) Conduit AP anymore

Summary
RN2903A based device joined directly after setting up the Conduit AP. A day later, they don’t join anymore, but still join to other Conduit AEP devices.

Join fail on: MTCAP-LNA3-915-001A Firmware1.4.4 LNSv1.0.41
Join OK on: MTCDT-H5-210A-US-EU-GB v1.4.3 LNSv1.0.31
Confirmed network server settings identical on the two devices.

Any feedback on how I can get the RN2903A based devices to join the Conduit AP would be greatly appreciated.

Detail
Summary of sequence of events.
# Configured Conduit AP
# Multiple units joined OK
# 2-way comms confirmed OK
# Approx. 1 day elapsed
# Units joined to other Conduit IP67 gateway v1.4.3 LNSv1.0.31 for undetermined amount of time.
# Power down other gateway
# Units did not join Conduit AP v1.4.4 LNS v1.0.41
# Power cycle end units.
# Soft reset network server
# Soft reset Conduit.
# Roll back LNS to v1.0.26
# Upgrade LNS back to v1.0.41
# Tried to manually add nodes based on [forum article|http://www.multitech.net/developer/forums/topic/join-issue-with-microchip-lora-radio-rn2903/]
# Join fail up until this point.
# Join OK within 45 s to Conduit v1.3.3 LNS v1.0.26.
# Join OK within 45 s to Conduit v1.4.3 LNS v1.0.31.

Conduit AP Network server configuration

{
  "udp": {
    "appPortUp": 1784,
    "appPortDown": 1786,
    "downstreamPort": 1782,
    "upstreamPort": 1780
  },
  "log": {
    "syslog": true,
    "path": "/var/log/",
    "console": true,
    "level": 50
  },
  "whitelist": {
    "enabled": true,
    "devices": []
  },
  "addressRange": {
    "start": "00:00:00:01",
    "end": "FF:FF:FF:FE"
  },
  "db": "/var/run/lora/lora-net-server.db",
  "mqtt": {
    "host": "127.0.0.1",
    "enabled": true,
    "port": 1883
  },
  "__v": 1,
  "test": {
    "disableRxWindow2": false,
    "disableDutyCycle": false,
    "disableRxWindow1": false,
    "disableRxJoin1": false,
    "disableRxJoin2": false
  },
  "lora": {
    "channelPlan": "US915",
    "frequencyBand": 915,
    "rx2Datarate": 8,
    "antennaGain": 3,
    "frequencyKR": 922900000,
    "frequencySubBand": 1,
    "dwelltimeUp": 0,
    "frequencyEU": 869500000,
    "netID": "000000",
    "dutyCyclePeriod": 60,
    "packetForwarderConfig": "",
    "frequencyAS": 922600000,
    "packetForwarderMode": false,
    "lbtEnabled": false,
    "rx1Delay": 1,
    "minDatarate": 0,
    "nodeQueueSize": 16,
    "maxEIRP": 20,
    "maxTxPower": 26,
    "rx1DatarateOffset": 0,
    "joinDelay": 5,
    "dwelltimeDown": 0,
    "enabled": true,
    "ADRStep": 30,
    "maxDatarate": 4,
    "enableStrictCounterValidation": false
  },
  "network": {
    "key": "<Key>",
    "leasetime": 86400,
    "name": "",
    "baseKey": "",
    "passphrase": "",
    "eui": "<EUI>",
    "salt": "",
    "public": true
  }
}

/var/log/messages shows debug regarding packet forwarder being quiet

2017-12-29T16:24:53.530626-08:00 mtcap lora-network-server: Packet forwarder not seen in 720 s
2017-12-29T16:25:23.530655-08:00 mtcap lora-network-server: Packet forwarder not seen in 750 s
2017-12-29T16:25:53.530751-08:00 mtcap lora-network-server: Packet forwarder not seen in 780 s