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Joined: Tue Jan 31, 2012 1:26 pm

Modem hunged up problem

Tue Jan 31, 2012 2:12 pm

Hi all,

I have about 20 411U routerboards with 3G WAN connection deployed in different towns and on couple of them I get following problem:
01:36:03 async,ppp,info PPP: initializing...
01:36:03 async,ppp,info PPP: reseting link...
01:36:04 async,ppp,info PPP: initializing modem...
01:36:04 async,ppp,info PPP: dialing out...
01:36:04 async,ppp,info PPP: terminating... - modem hunged up
01:36:04 async,ppp,info PPP: disconnected

All routerboards have the same PPP-client configuration, same OS (5.8), same 3G provider, same modems, everything except LAN config (which is irrelevant for this problem)...
This is configuration for PPP-client:
name="PPP" max-mtu=1500 max-mru=1500 mrru=disabled port=usb2 data-channel=0
info-channel=0 apn="*****" pin="" user="" password="" profile=default phone=""
dial-command="ATDT" modem-init="" null-modem=no dial-on-demand=no add-default-route=no
use-peer-dns=yes keepalive-timeout=30 allow=pap,chap,mschap1,mschap2

Routerboard reboots do not help, nor do modem resets. Could anyone explain what is the reason for this problem, please?
Posts: 338
Joined: Tue Feb 24, 2009 11:23 pm

Re: Modem hunged up problem

Tue Jan 31, 2012 4:10 pm

Usually this happens when the modem has some kind of hickup and needs a power-cycle (unplug/replug)
to work normally again. Unfortunately, RB411U does not support USB power-reset.

To test this, try opening a serial-terminal on the data channel (disable ppp-client first),
and try ATDT*99***1# - you should get the error message "NO CARRIER".

A workaround that sometimes helps (if this still occurs after modem unplug/replug),
is to remove APN name from routeros configuration,
and use init string AT+CGDCONT=1,"IP",""
and use phone number *99#

I needed to use that to make some versions of Huawei E160 work correctly.
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Posts: 5
Joined: Tue Jan 24, 2012 10:33 am

Re: Modem hunged up problem

Wed Feb 01, 2012 3:02 pm

Unfortunately, RB411U does not support USB power-reset.
I have RB751U-2HnD's and RB433UAH's which also have this problem. It would be nice to have an option to make a USB power reset. It could be used as a script to automate te process.
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MikroTik Support
Posts: 3443
Joined: Mon May 31, 2004 2:55 pm

Re: Modem hunged up problem

Thu Feb 02, 2012 1:49 pm

maybe this troubleshooting link could help you: ... s_to_check

maybe this could help you to reset the modem:
After executing some AT commands the modem doesn't respond correctly or reports error values
* resetting the modem functionality might solve the problem
* use /system serial-terminal usbX channel=X
* execute the at+cfun=0 command and wait few seconds and execute at+cfun=1
Also add async,debug topics in the logging so you could see what exactly the modem didn't like.

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