Gateway is not connected

I have RPi + ic880a gateway. On console it shows it is not connected. I checked the thread. The logs are following.

>> sudo tcpdump -AUq port 1700

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on wlan0, link-type EN10MB (Ethernet), capture size 262144 bytes
15:19:55.812079 IP 10.241.76.148.45111 > 52.169.76.203.1700: UDP, length 12
E..(.j@.@..a
.L.4.L..7.......3...'....P.
15:19:55.948331 IP 52.169.76.203.1700 > 10.241.76.148.45111: UDP, length 4
E.. {&@.....4.L.
.L....7.....3............
15:20:00.756840 IP 10.241.76.148.49884 > 52.169.76.203.1700: UDP, length 251
E....^@.@..~
.L.4.L..........f+..'....P.{"stat":{"time":"2018-06-12 13:20:00 GMT","lati":44.80371,"long":20.50800,"alti":11,"rxnb":0,"rxok":0,"rxfw":0,"ackr":100.0,"dwnb":0,"txnb":0,"pfrm":"IMST + Rpi","mail":"r.bohara@digital-worx.com","desc":"rp3-ic880a-digital-worx gateway"}}
15:20:00.887498 IP 52.169.76.203.1700 > 10.241.76.148.49884: UDP, length 4
E.. ~s@.-..`4.L.
.L.......0..f+...........
15:20:05.842024 IP 10.241.76.148.45111 > 52.169.76.203.1700: UDP, length 12
E..(..@.@...
.L.4.L..7...........'....P.
15:20:05.957977 IP 52.169.76.203.1700 > 10.241.76.148.45111: UDP, length 4
E.. ..@.....4.L.
.L....7..................
15:20:15.952031 IP 10.241.76.148.45111 > 52.169.76.203.1700: UDP, length 12

syslog

>>sudo tail -f /var/log/syslog
Jun 12 15:04:57 ttn-gateway ttn-gateway[26651]: # TX errors: 0
Jun 12 15:04:57 ttn-gateway ttn-gateway[26651]: ### [GPS] ###
Jun 12 15:04:57 ttn-gateway ttn-gateway[26651]: # Invalid gps time reference (age: 1528808670 sec)
Jun 12 15:04:57 ttn-gateway ttn-gateway[26651]: # Manual GPS coordinates: latitude 44.80371, longitude 20.50800, altitude 11 m
Jun 12 15:04:57 ttn-gateway ttn-gateway[26651]: ##### END #####
Jun 12 15:04:57 ttn-gateway ttn-gateway[26651]: INFO: [up] PUSH_ACK for server router.eu.thethings.network received in 48 ms
Jun 12 15:04:57 ttn-gateway ttn-gateway[26651]: INFO: [down] for server router.eu.thethings.network PULL_ACK received in 60 ms
Jun 12 15:04:57 ttn-gateway ttn-gateway[26651]: INFO: [down] for server router.eu.thethings.network PULL_ACK received in 59 ms
Jun 12 15:06:30 ttn-gateway kernel: [149808.888691] device wlan0 left promiscuous mode
Jun 12 15:06:30 ttn-gateway rsyslogd-2007: action 'action 17' suspended, next retry is Tue Jun 12 15:08:00 2018 [try http://www.rsyslog.com/e/2007 ]
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: INFO: [down] for server router.eu.thethings.network PULL_ACK received in 192 ms
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: ##### 2018-06-12 13:05:00 GMT #####
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: ### [UPSTREAM] ###
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # RF packets received by concentrator: 0
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # CRC_OK: 0.00%, CRC_FAIL: 0.00%, NO_CRC: 0.00%
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # RF packets forwarded: 0 (0 bytes)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # PUSH_DATA datagrams sent: 1 (251 bytes)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # PUSH_DATA acknowledged: 100.00%
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: ### [DOWNSTREAM] ###
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # PULL_DATA sent: 3 (100.00% acknowledged)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # PULL_RESP(onse) datagrams received: 0 (0 bytes)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # RF packets sent to concentrator: 0 (0 bytes)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # TX errors: 0
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: ### [GPS] ###
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # Invalid gps time reference (age: 1528808700 sec)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # Manual GPS coordinates: latitude 44.80371, longitude 20.50800, altitude 11 m
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: ##### END #####
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: INFO: [down] for server router.eu.thethings.network PULL_ACK received in 108 ms
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: INFO: [down] for server router.eu.thethings.network PULL_ACK received in 136 ms
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: INFO: [down] for server router.eu.thethings.network PULL_ACK received in 123 ms
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: ##### 2018-06-12 13:05:30 GMT #####
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: ### [UPSTREAM] ###
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # RF packets received by concentrator: 0
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # CRC_OK: 0.00%, CRC_FAIL: 0.00%, NO_CRC: 0.00%
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # RF packets forwarded: 0 (0 bytes)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # PUSH_DATA datagrams sent: 1 (251 bytes)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # PUSH_DATA acknowledged: 0.00%
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: ### [DOWNSTREAM] ###
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # PULL_DATA sent: 3 (100.00% acknowledged)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # PULL_RESP(onse) datagrams received: 0 (0 bytes)
Jun 12 15:07:17 ttn-gateway ttn-gateway[26651]: # RF packets sent to concentrator

ttnctl status log

>>ttnctl gateway status eui-B827EBFFFE1450A1
  INFO Discovering Router...                   
  INFO Connecting with Router...               
  INFO Connected to Router                     
  INFO Received status                          GatewayID=eui-b827ebfffe1450a1

           Last seen: 2018-06-12 15:31:00.78368879 +0200 CEST
           Timestamp: 0
       Reported time: 2018-06-12 15:31:00 +0200 CEST
         Description: rp3-ic880a-digital-worx gateway
            Platform: IMST + Rpi
       Contact email: r.bohara@digital-worx.com
      Frequency Plan: EU_863_870
              Bridge: "ttn-bridge-eu" 2.x.x-04b47381cd9bccae430251deb09102a7b218de66 (2018-02-20T16:19:59Z) PacketForwarder Backend
          IP Address: 93.87.19.154
            Location: (44.803711, 20.507999; source unknown)
                 Rtt: not available
                  Rx: (in: 0; ok: 0)
                  Tx: (in: 0; ok: 0)

What could be a problem here.

Have you registered the gateway with ‘legacy’ protocol? And does the gateway ID as listed in local_conf.json match the gateway ID you registered?