LTE5388-M804 loses network after some time

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RobTheNetworkGuy
RobTheNetworkGuy Posts: 14  Freshman Member
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edited January 4 in Mobile Broadband
I am using the LTE5388 in IP passthrough mode with all wifi radios turned off. It's connected to a pfsense router (I use it as the failover WAN connection).

Today I tested the failover. pfSense pings the LTE5388 modem and these pings are returned so pfSense thinks the connection is working. But no packets seem to enter the LTE5388 from the WAN.

I connect to the admin interface of the LTE5388. It says that connectivity is good. But when I use its diagnostic interface (under maintenance/diagnostic) to ping an IP address, no packets are returned.

I tried running its diagnostic speed test but of course it could not download the configuration file.

The uptime is 12 days.

I rebooted the LTE5388. Now everything is working perfectly.

I would like it to work more reliably than this as failover should not require any intervention such as rebooting. If it is some software instability I would like to help diagnose it. But perhaps it is some higher level issue, perhaps with the LTE connection (although this was not apparent in the interface anywhere).

My firmware is V1.00(ABSQ.4)C0

So my question has two parts:
a) is there any configuration I should check
b) if this happens again, what can I do to provide more information to diagnose the problem.

Thanks!
Rob.


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  • tonygibbs16
    tonygibbs16 Posts: 901  Guru Member
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    edited January 2023
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    Hello @RobTheNetworkGuy

    Are you saying the Ping/Traceroute/NSLOOKUP diagnostic features under Maintenance->Diagnostic were unaccessible?
           - Shown in section 35.3 of the user guide available at https://download.zyxel.com/LTE5388-M804/user_guide/LTE5388-M804_EU_1.00_2.00%20Ed2.pdf 

    What do Cellular Info pages show please?

    To answer your questions, I think:
      a. Test Ping from within the web interface if possible.
      b. Cellular Info screen details I think.

    Kind regards,
         Tony
  • RobTheNetworkGuy
    RobTheNetworkGuy Posts: 14  Freshman Member
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    The diagnostic *page* worked just fine. But the pings were not getting responses.

    I remember that the cellular information made the connection *look* healthy, but there may well have been a clue that something was wrong. Unfortunately I did not record the full contents of the pages before I just tried rebooting. If it happens again I will update here.

    Thanks for the answer; it does answer my question but there may be more to learn so my instinct is to not mark it as answered until we can get a more complete understanding.
  • RobTheNetworkGuy
    RobTheNetworkGuy Posts: 14  Freshman Member
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    A minor update to this: I changed the monitor address to be a DNS server from my mobile ISP and configured a static route so that these packets are always routed via the Zyxel modem. Eight days later at 7.25am my pfSense router emailed me to say the Zyxel was offline.

    Unfortunately I can neither ping it nor access the web interface. I don't suppose there is any other diagnostic that can be done. There are three green lights: power, WAN and LTE. Wifi and phone lights I would not expect to be on. On the back the Ethernet light is blinking.

    Now I have power-cycled it (at 8:10am). By 8:12 everything is working again.

    8:15 I am trying to access the web interface of the Zyxel to see if there are any log messages. I got to the login page but when I enter my credentials I am faced with a spinning donut. And I can't ping it any more or the test address any more. The WAN light is flashing, though.

    8:23 power cycling again. Same sequence. Everything seems fine but I can't get past the Zyxel admin login page and after a minute or so I stop being able to ping the Zyxel.

    8:28 power cycling again. 8:30 I can ping the Zyxel. I have power and WAN lights. 8:31 I have a green LTE light. Immediately the pings from the Zyxel have stopped working. The WAN light is flashing. Could it be downloading firmware? I will leave it for a while.
  • RobTheNetworkGuy
    RobTheNetworkGuy Posts: 14  Freshman Member
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    9:02 -- I still can not ping the Zyxel modem or access its web interface. However I do seem to be able to ping the monitor address (the DNS server I access via the modem). Tracepath confirms that packets to that address are routed via the Zyxel.

    I will do more investigation later.
  • MatteP99
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    I have the same problem with the LTE5398-M904.

    I think when the DHCP lease of the public ip expires, the modem/router cannot renew the lease. I think so because every time you drop the connection and restart it, the modem/router has a new public ip address and starts working normally again.

    I have searched all the web interface pages to find a way to be able to renew the lease manually, but there doesn't seem to be any way.

    At this point I think if a solution is not found I will have to change modem/router.
  • RobTheNetworkGuy
    RobTheNetworkGuy Posts: 14  Freshman Member
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    Thanks for that insight, MatteP99. I will look out for it.

    I am back here because it happened again and I did not find out until my wife called me to complain that there is no internet. All this effort and expense to set up failover and this happens…

    It is my fault that I did not notice the email a few days ago warning me that there was no connection on the LTE WAN.

    I wonder: is there a way to remotely reboot the device? I could set up a script that does so whenever the connection fails.

    A firmware fix would be a better solution. How do we get the attention of Zyxel engineers?

    Next time this happens I will try to get more diagnostic information.

  • JeanFrancois
    JeanFrancois Posts: 45  Freshman Member
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    Same problem reported with the other LTE router (see https://community.zyxel.com/en/discussion/16294/zyxel-lte5398-m904-connected-to-the-cellular-network-but-no-internet-access)

    2 features should be urgely added:

    • an optionnal IP monitoring to detect the network issue and automatically renew the LTE connection
    • a lease time parameter to force the router to renew its DHCP parameters every x minutes or hours

    Those features are really "standard" in network devices and shouldn't be difficult to add in a firmware update.

    Note: if you use pfSense to detect the issue with gateway monitoring, obviously it will disable the route to the router and you cannot manage it anymore... bad idea ;-)

  • JeanFrancois
    JeanFrancois Posts: 45  Freshman Member
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    @MatteP99: go to Network Setting > Broadband > Cellular Band and then re-apply
    manual bands selection to force LTE reconnection. If you are in "manual" mode you don't have to change the settings, overwise select and apply "manual" and then revert to "auto". It will disconnect and reconnect to LTE network within a few seconds.

  • RobTheNetworkGuy
    RobTheNetworkGuy Posts: 14  Freshman Member
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    I wonder if there is a way to do this with a CLI. If so, it could be scripted (at least until a proper fix is made).

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