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3 Posts

02-13-2019

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4G modem loses connection and wants APN

2019-02-13, 12:46 PM

Sometimes my 4G modem (X1 Carbon) loses connection. It then whines about missing or wrong APN (even though the one I've always used is still there and is "applied").

 

A reboot didn't work, but later when I started the machine up again it magically worked again. There didn't seem to be any new driver updates....so what to do?

 

And don't say delete the APN and type it in again. That has been tried....many many times.

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70 Posts

05-10-2016

HK

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Re: 4G modem loses connection and wants APN

2019-02-13, 13:36 PM

Hi eLVeeJay,

 

It may sometimes led by a deffective SIM card indeed. See if you can find another SIM to test for 1 or 2 days, and check if same problem happened still.

 

"May the Force be with Lenovo"
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3 Posts

02-13-2019

DK

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Re: 4G modem loses connection and wants APN

2019-02-13, 14:09 PM

Thank you for your fast reply.

 

Hm...it might be that. It happened while on a moving train (so many changes to the antennae it connects to). 

 

I've had problems before, and a driver update solved that, so I will always suspect the modem first (or its software).

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42 Posts

09-07-2016

US

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  • Message 4 of 9

Re: 4G modem loses connection and wants APN

2019-02-13, 18:17 PM

I have the exact same problem you are describing on my X1 Yoga 2nd with em7455 on T-Mobile. It drives me nuts. I tried everything: new drivers, latest firmware from Sierra Wireless Source. I even tried going from MBIM to QMI mode. I highly doubt it is the SIM's fault. Usually if I do at!reset command on the modem's com port, I can reconnect. Also at!gstatus? indicates still attached to LTE. Something messed up in the network stack. One time when it happened the modem went into low-power state. I am going to try disabling LPM.

 

Mine also happens on a moving train. I think it does not recover well from a temporary signal loss.

 

I never had this problem on my X1 Yoga 1st with em7455 on the train. I wonder if it is linked to Windows 10 1809 update.

 

In Mobile Broadband advanced settings what APN have you set? And is it IPV4, IPV6 or IPV4V6 or even IPV4V6XLAT (those are the choices I see).

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12648 Posts

06-06-2011

RU

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  • Message 5 of 9

Re: 4G modem loses connection and wants APN

2019-02-14, 7:26 AM
guho,

when the connection is lost, is the SIM card still recognizable? Check it either by AT command or by netsh in the command prompt window:
netsh mbn sh read int=*



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3 Posts

02-13-2019

DK

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  • Message 6 of 9

Re: 4G modem loses connection and wants APN

2019-02-21, 10:47 AM

At least I'm not the only one with this problem. I've tried to enable and disable the device, and after some time doing that it starts to work again...until it fails again.

 

It would be nice if Lenovo fixed this once and for all....

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42 Posts

09-07-2016

US

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  • Message 7 of 9

Re: 4G modem loses connection and wants APN

2019-02-25, 14:40 PM
There is a new BIOS for the x1 yoga 2, which I upgraded to this morning, and I have not had this happen to me on the train today. Not sure if it is connected. Hope there are updates for your x1 carbon too.
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61 Posts

06-19-2018

AU

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  • Message 8 of 9

Re: 4G modem loses connection and wants APN

2019-02-25, 21:28 PM

i've had a bit more stability by manually entering APN rather than 'automatic" APN

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9 Posts

11-26-2015

US

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  • Message 9 of 9

Re: 4G modem loses connection and wants APN

2019-09-12, 23:30 PM
I have the same issue on my X1 Gen5. Use on train, cellular card often loses connection. Get the "APN" error often. Usually have to do full reboot to get things working again.
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