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Frequent connection loss with Zyxel LTE7460 (v2)

kerraykerray Posts: 4  Junior Member
edited October 7 in Questions
Hello, 
I've been using Zyxel LTE7460 for over a year now and it often drops connection.

It's been more frequent when there are too many people around the cell tower we connect to, but now it keeps happening even in times when there's noone around, and internet connection is dropping every few minutes, which is exhausting - particularly when a small Huawei LTE box keeps better connection inside behind a wall than LTE7460 has mounted on a pole 8m above ground.

A year ago I thought that maybe a firmware update is coming, but there has been none, so I'm basically posting this to find out if this is a common issue or if I have a faulty piece, or if anyone has any idea...

I couldn't see anything suspicious in the logs, so now I've started NXLog server on my machine in case there are some lost log entries, and now I can see the drops (the log is interlaced with my Asus router log - used as AP)

Thanks for any help or pointers!

This is what the logs look like around a connection drop:
<30>Oct  5 09:49:00 LTE7460 malmanger[726]: srv_sms_get_sms_new_incoming_count: srv_sms_get_sms_new_incoming_count
<3>Oct  5 09:49:04 LTE7460 kernel: [  175.056911] 
<3>Oct  5 09:49:04 LTE7460 kernel: [  175.056911] SMSM: Modem SMSM state changed to SMSM_RESET.
<3>Oct  5 09:49:04 LTE7460 kernel: [  175.061424] Fatal error on the modem.
<3>Oct  5 09:49:04 LTE7460 kernel: [  175.065147] modem subsystem failure reason: lte_ml1_schdlr2_stm.c:1265:Assertion 0 failed.
<6>Oct  5 09:49:04 LTE7460 kernel: [  175.073379] subsys-restart: subsystem_restart_dev(): Restart sequence requested for modem, restart_level = SYSTEM.
<30>Oct  5 07:47:16 LTE7460 malmanger[724]: srv_nw_init: Cellular: network init.
<30>Oct  5 07:47:16 LTE7460 malmanger[724]: srv_uim_read_pbm_records_ind: srv_uim_read_pbm_records_ind WNC_MAL_PBM_PB_STATE_READY
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: registration_state: 2
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: radio_technology: 0
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: current_plmn_name: 
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: srv_capability: 3
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: sim_rej_info: 1
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_home_operator: Cellular: mcc_mnc_ascii: 23001
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_web_init: SystemMaintenance: Initial function.
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_web_get_imei: SystemMaintenance: imei=359840070060641
<6>Oct  5 07:47:17 LTE7460 kernel: [   33.746207] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
<5>Oct  5 07:47:17 LTE7460 kernel: [   33.751924] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<6>Oct  5 07:47:17 LTE7460 kernel: [   33.768318] br0: port 1(eth0) entered forwarding state
<6>Oct  5 07:47:17 LTE7460 kernel: [   33.772495] br0: port 1(eth0) entered forwarding state
<5>Oct  5 07:47:17 LTE7460 kernel: [   33.780261] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: registration_state: 0
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: radio_technology: 0
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: current_plmn_name: 
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: srv_capability: 2
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: sim_rej_info: 1
<30>Oct  5 07:47:17 LTE7460 malmanger[724]: srv_fw_firewall_operation: Firewall: NAT restart...
<30>Oct  5 07:47:18 LTE7460 malmanger[724]: srv_fw_firewall_operation: Firewall: DosAttack restart...
<30>Oct  5 07:49:46 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: registration_state: 1
<30>Oct  5 07:49:46 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: radio_technology: 8
<30>Oct  5 07:49:46 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: current_plmn_name: T-Mobile CZ
<30>Oct  5 07:49:46 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: srv_capability: 3
<30>Oct  5 07:49:46 LTE7460 malmanger[724]: srv_nw_update_reg_state: Cellular: sim_rej_info: 1
<30>Oct  5 07:49:46 LTE7460 malmanger[724]: srv_fw_firewall_operation: Firewall: RemoteManagement restart...
<30>Oct  5 07:49:46 LTE7460 malmanger[724]: srv_fw_firewall_operation: Firewall: UPnP restart...
<30>Oct  5 07:49:47 LTE7460 malmanger[724]: srv_fw_firewall_operation: Firewall: port forwarding restart...
<30>Oct  5 07:49:47 LTE7460 malmanger[724]: srv_fw_firewall_operation: Firewall: icmp restart...
<30>Oct  5 07:49:47 LTE7460 malmanger[724]: srv_fw_firewall_operation: Firewall: qos restart...
<30>Oct  5 07:49:47 LTE7460 malmanger[724]: srv_fw_firewall_operation: Firewall: dmz restart...
<5>Oct  5 07:49:47 LTE7460 kernel: [   36.692659] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<30>Oct  5 07:49:48 LTE7460 malmanger[724]: srv_fw_ipv6_firewall_operation: Firewall: IPv6 DosAttack restart...
<5>Oct  5 07:49:48 LTE7460 kernel: [   37.348672] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<5>Oct  5 07:49:48 LTE7460 kernel: [   37.410801] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<30>Oct  5 07:49:48 LTE7460 malmanger[724]: srv_fw_ipv6_firewall_operation: Firewall: IPv6 RemoteManagement restart...
<5>Oct  5 07:49:48 LTE7460 kernel: [   37.600419] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<5>Oct  5 07:49:48 LTE7460 kernel: [   37.616885] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<5>Oct  5 07:49:48 LTE7460 kernel: [   37.826303] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<5>Oct  5 07:49:48 LTE7460 kernel: [   37.856163] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<30>Oct  5 07:49:48 LTE7460 malmanger[724]: srv_fw_ipv6_firewall_operation: Firewall: IPv6 qos restart...
<5>Oct  5 07:49:48 LTE7460 kernel: [   37.874822] r8152 1-1:1.0 eth0: Promiscuous mode enabled
<30>Oct  5 07:49:49 LTE7460 udhcpc[3593]: udhcpc (v1.24.1) started
<30>Oct  5 07:49:49 LTE7460 udhcpc[3593]: Sending discover...
<30>Oct  5 07:49:49 LTE7460 udhcpc[3593]: Sending select for 100.x.x.80...
<4>Oct  5 07:49:49 LTE7460 kernel: [   38.140912] NOHZ: local_softirq_pending 08
<30>Oct  5 07:49:49 LTE7460 malmanger[724]: _ntp_update_time: NTP: Sync time with cellular network start..
<30>Oct  5 07:49:49 LTE7460 udhcpc[3593]: Lease of 100.x.x.80 obtained, lease time 7200
<30>Oct  5 07:49:49 LTE7460 malmanger[724]: _ntp_update_time: NTP: Get nitz time = 2019/10/5 07:49:49+8,01


#SP_Oct_2019
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Answers

  • bbbbbb Posts: 29  Junior Member
    Hi Kerray, 

    Could you please confirm the following questions?
    1. Is your LTE7460 firmware version V1.00(ABFR.4)C0?
    2. When the LTE7460 disconnects from the network, could it reconnect automatically without any manual intervention (e.g.  a reboot)?
    3. Does the issue happen from the very beginning when you start using the LTE7460?
    4. Could you please switch the "Network Selection" to manual mode and start scanning when you disconnect from the network? It takes about 1 minute to show a list. Once it shows a list, I would like to know whether T-Mobile CZ's network is on the list. 



    5. Could you please check your network coverage from the following website? Please specify the network as "T-Mobile" first, zoom in to the place where the LTE7460 locates, switch to different frequency and check whether the place is overlapped by multiple frequency signal. 
    https://digi.ctu.cz/lte-pokryti/

    Regards, 

    Bob
  • kerraykerray Posts: 4  Junior Member
    Hi, 
    1. my firmware version is V1.00(ABFR.3)C0
    2. it mostly reconnects automatically after resetting itself, but even complete hangups happen from time to time
    3. it's been happening from the start - most of the time it's been barely noticeable, but our weak signal is cut off quite often even on the Huawei whenever a public gathering happens under "our" cell tower, or even just in the evenings when more people are home
    4. I get a timeout right now trying to do the scan, coinciding with very frequent resets, I'll try again
    5. the same with the coverage website - I can't tell you the frequencies from the top of my head, but we do have some LTE coverage :) I tried even switching to 3G only, didn't seem to help with the disconnects, but maybe it could log some other useful information 
  • kerraykerray Posts: 4  Junior Member
    Ok, now I got number 4 through: there's plenty of LTE800, some LTE1800, some LTE2100. 
  • bbbbbb Posts: 29  Junior Member
    Hi Kerray,

    From your descriptions I think that the issue is attributed by the cell deployment and the LTE7460's design. 

    First, when the site is crowded, the service quality within each cell degrades. It not only affects the coverage where the cell can serve but also the downlink and uplink speed. It might be better if T-Mobile can deploy more intensive infrastructure nearby.

    Second, the LTE7460's LTE antenna is directional, which implies that users have to position the device to a correct direction. It is different from most of indoor routers of which the antenna can serve all directions. May I know whether your LTE7460 was carefully positioned before mounting to the pole?

    Regards,

    Bob
  • kerraykerray Posts: 4  Junior Member
    Yep, I know about the crowding effects, and there's nothing I can do with that. However, the antenna is positioned to face the cell tower - it can go much faster than the little Huawei box inside. But when conditions get worse, the Huawei box behind a brick wall can hold on much better than the antenna on its pole. I'll check the antenna direction.

    The thing is, I think getting disconnected and having bad signal can be expected with an LTE modem, and shouldn't cause it to crash/restart itself even if happens every 5 minutes, and events in the log don't seem to indicate the reset was cause by weak signal - at least on the surface.


  • bbbbbb Posts: 29  Junior Member
    Hi Kerray, 

    Does it mean that the LTE7460 would reboot the whole unit every 5 minutes or in a short time interval?

    Regards, 

    Bob
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