u3g Sierra Wireless LTE device disconnects ppp after 2-3MB of outgoing traffic

[Adrian Gschwend]

On 11.12.19 21:24, mike tancsa wrote:

> Do you have LQR/ech enabled ?  Here is the ppp.conf section I use
yeah, it's pretty much based on what you proposed, main change was APN.

Later I did add

set reconnect 3 5

Hoping that this adds something but apparently it does not.

> Depending on your modem, some Sierra's dont allow the GSTATUS command
> from the management port, just signal info. Eg. port /dev/cuaU0.3 is my
> data port to make my ppp connection on, I can connect to cuaU1.4 to ask
> some basic info like signal.  Sierra should have a pretty good AT
> command set manual free to download so you can see what is exactly
> available.

yes I have that one.

> % cu -l /dev/cuaU1.4
> Connected
> Sierra Wireless, Incorporated
> MC7700
> APP1
> 
> OK
> +CSQ: 21,99
> OK

That does not work on mine, on 2 I get "all ports are connected" but
that's where PPP is running on. On the others I get "connected" but
never any output (and also no echo)

> for whatever reason, ate1 is not respected, so my commands dont show.
> the above is the output of entering ati and at+csq

I've seen that too

>  set lqrperiod 10
>  enable lqr
>  enable echo
> 
> should allow ppp to reconnect should ppp disconnect.

unfortunately it doesn't. The link seems still up but absolutely nothing
goes through anymore.

The only thing I can do is kill ppp and restart it, then I have a link
again immediately.

> you should in your logs see
> 
>  ppp[3416]: tun10: LCP: deflink: SendEchoRequest(80560) state = Opened
>  ppp[3416]: tun10: LCP: deflink: RecvEchoReply(176) state = Opened

jep:
ppp[57554]: tun0: LCP: deflink: RecvEchoReq: magic 0x245182f7 is wrong,
expecting 0x6745dd7e
ppp[57554]: tun0: LCP: deflink: SendEchoReply(217) state = Opened
ppp[57554]: tun0: LCP: deflink: RecvEchoReply(217) state = Opened
ppp[57554]: tun0: LCP: deflink: SendEchoRequest(986) state = Opened

not sure what's going on with the wrong magic. Maybe that link is simply
really unreliable.

regards

Adrian