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lucasasdelli
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Posts: 37
Joined: Fri Apr 12, 2013 11:18 am
Location: Bologna, Italy

SXT LTE6 Partial disconnections

Mon Aug 16, 2021 5:22 pm

Hi,

we've 5 SXT LTE6 routers and wireless signal is quite high (RSRP -70dBm, RSRQ between -12dB and -8dB).
LTE firmware is R11e-LTE6_V028, supplied from support.
Sometimes one of the routers loses connection: ping is OK, DNS is OK but no browsing nor streaming etc.
On each SXT I've put more routes, with higher weight, so that if the LTE local route fails, an alternate SXT is used to resolve client requests, but because ping is anyway working, this won't cure the issue.
During the issue, LTE parameters read correctly.
To solve it, an USB reboot is needed.
This happens on more of our SXTs.

Any ideas?
Thanks!
Luca
 
Zacharias
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Posts: 3459
Joined: Tue Dec 12, 2017 12:58 am
Location: Greece

Re: SXT LTE6 Partial disconnections

Mon Aug 16, 2021 7:35 pm

What do you mean by disconnection ?
Does the LTE interface goes down ? R flag missing ?
Or the LTE is Running ?

You can export your configuration with hide-sensitive parameter and post it so we can have a look...
 
lucasasdelli
newbie
Topic Author
Posts: 37
Joined: Fri Apr 12, 2013 11:18 am
Location: Bologna, Italy

Re: SXT LTE6 Partial disconnections

Mon Aug 16, 2021 8:20 pm

What do you mean by disconnection ?
Does the LTE interface goes down ? R flag missing ?
Or the LTE is Running ?

You can export your configuration with hide-sensitive parameter and post it so we can have a look...
Hi Zacharias,
thank you for answering!
The LTE interface remains ok, like the LTE readings within good margins registered and with full flag.
Clients could do ping to internet, as well as resolve DNS (directly or via the SXT DNS cache), but any attempt to open an http stream causes timeout.
In those conditions, the only way to resume is to do an LTE USB reset.
Anyway, it could happen 1-2 times per day, so I would be satisfied if we can write a script that could detect that malfunction, and then do a reset by itself. Unfortunately I'm unable to trap the abnormal status. I've tried to do periodic ROS version checks, but they always succeed so the malfunction is not detected.

I've attached config as per your kind request

Thanks!
Luca
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Zacharias
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Posts: 3459
Joined: Tue Dec 12, 2017 12:58 am
Location: Greece

Re: SXT LTE6 Partial disconnections

Mon Aug 16, 2021 8:28 pm

Use /export hide-sensitive and post your code inside code tags...
 
lucasasdelli
newbie
Topic Author
Posts: 37
Joined: Fri Apr 12, 2013 11:18 am
Location: Bologna, Italy

Re: SXT LTE6 Partial disconnections

Mon Aug 16, 2021 8:43 pm

Use /export hide-sensitive and post your code inside code tags...
Some more details, should they be useful.
With the issue present, by disabling LTE interface the alternate routing act as expected, so the clients could browse internet normally, directed to another SXT. Therefore it shouldn't be anything related with Ethernet side, I guess.
The MTU has been lowered as the most successful value with this connection; I have same issue even by set it at 1500.
When operating, rate is up to 60Mbps downstream and 30Mbps upstream.
There are even two DDNS schedules (not reported in config), working by calling a webhook, and they work well anyway, even with the problem active.
It looks as if some issues are within the routing itself, as if the SXT refuses to route some packets from LAN to LTE.

Luca
 
lucasasdelli
newbie
Topic Author
Posts: 37
Joined: Fri Apr 12, 2013 11:18 am
Location: Bologna, Italy

Re: SXT LTE6 Partial disconnections

Wed Aug 18, 2021 7:41 pm

Use /export hide-sensitive and post your code inside code tags...
Some other infos about the issue.
I've configured our Zabbix server to regularly check (web scenarios) three websites (forced to one SXT via static routes) and to issue an API LTE reset when all fails.
The error reported by Zabbix upon failure is "No route to host" for all https checks. An LTE USB reset solves it.
So some packets like icmp, dns etc are correctly routed to the internet, while http connections doesn't obtain a valid route and does fail.

This behavior is noticed on all our five SXT LTE6 routers. I suspect a bug.
Cheers
Luca

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