Modem Disconnecting

Sierra Wireless AirPrime Modem Card Topics
Cheburashka
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Re: Modem Disconnecting

Post by Cheburashka » Sun Apr 15, 2018 7:30 pm

Actually I'm back to periodic disconnects.. :(

When it disconnects, it looks like the router admin page is also inaccessible.

I'll try cleaning the SIM card as well, although not sure how it could become dislodged.

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Jflex113
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Re: Modem Disconnecting

Post by Jflex113 » Tue Apr 17, 2018 5:00 am

Do you have the modem reconnect enabled? If you have it set to router reboot during a lose of ping then that can happen.

It should look like this when enabled with modem reconnect if you are using it.

Modem Reconnect 1.jpg


If the router reboots every time you loose internet connection then this setting (if it is selected) could be your issue.

Modem Reconnect 2.jpg


I would check this to eliminate one possible cause of the router not being accessible during a lose of internet.
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Brady_ls
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Re: Modem Disconnecting

Post by Brady_ls » Wed Apr 18, 2018 9:35 pm

JimHelms wrote:
Sun Apr 15, 2018 7:17 am
Brady_ls wrote:
Sat Apr 14, 2018 6:24 pm
I tried re-flashing firmware and Configuring the MC7455. Same issue, but here is connection log and debug info from after ding this.

Sat Apr 14 23:18:36 2018 : /dev/ttyUSB1 AT+CGDCONT?
+CGDCONT: 1,"IPV4V6","r.ispsn","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
The logs you posted really does not tell much other than showing r.ispsn is the APN you are trying to connect to the network with. Need to copy and past the reset of the information with the antenna signals that will be in that same window.

I also assume your APN is r.ispsn on your hotpot as opposed to n.ispsn?



Hi Jim,

I ran through each step in the troubleshooting, and no dice... my APN is the r.ispsn not n.

Here is the copy paste from debug....

Code: Select all

Current Time:  1483		Temperature: 21
Reset Counter: 1		Mode:        ONLINE         
System mode:   LTE        	PS state:    Not attached 
LTE band:      B25    		LTE bw:      10 MHz  
LTE Rx chan:   8640		LTE Tx chan: 4294967295
LTE CA state:  NOT ASSIGNED
EMM state:     Deregistered   	Attach Needed  
RRC state:     RRC Idle       
IMS reg state: No Srv  		
PCC RxM RSSI:  -76		RSRP (dBm):  -109
PCC RxD RSSI:  -75		RSRP (dBm):  -106
Tx Power:      0		TAC:         5001 (20481)
RSRQ (dB):     -14.8		Cell ID:     0A001700 (167778048)
SINR (dB):     -2.6
OK

Code: Select all

Thu Apr 19 02:34:08 2018 : /dev/ttyUSB1 AT+CSQ
+CSQ: 19,99
OK
AT*CNTI=0
+CME ERROR: no network service
AT!SELRAT?
!SELRAT: 06, LTE Only
OK
AT+ECIO?
+ECIO: NOT IMPLEMENTED
OK
AT+RSCP?
+RSCP: NOT IMPLEMENTED
OK
AT!UMTSCHAN?
!UMTSCHAN: NOT IMPLEMENTED
OK

Code: Select all

AT!GSTATUS?
!GSTATUS: 
Current Time:  1494		Temperature: 21
Reset Counter: 1		Mode:        ONLINE         
System mode:   LTE        	PS state:    Not attached 
LTE band:      B26    		LTE bw:      5 MHz   
LTE Rx chan:   8763		LTE Tx chan: 4294967295
LTE CA state:  NOT ASSIGNED
EMM state:     Deregistered   	Attach Needed  
RRC state:     RRC Idle       
IMS reg state: No Srv  		
PCC RxM RSSI:  -66		RSRP (dBm):  -96
PCC RxD RSSI:  -67		RSRP (dBm):  -102
Tx Power:      0		TAC:         5001 (20481)
RSRQ (dB):     -15.6		Cell ID:     0A001F10 (167780112)
SINR (dB):     -1.6
OK

Brady_ls
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Re: Modem Disconnecting

Post by Brady_ls » Wed Apr 18, 2018 9:46 pm

Modem> Network Status> General Information> Modem jumps between "Sierra Wireless, Incorporated MC7455" and "no modem present."

"Does no modem present" refer to communication between the router and the card?

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Jflex113
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Re: Modem Disconnecting

Post by Jflex113 » Wed Apr 18, 2018 10:43 pm

Is your modem inside a router like a ZBT or is it in an enclosure? If it is in an enclosure I'm wondering if the usb cable is not good enough and that might be causing these disconnects possibly.
"If you're going to be ignorant, you'd better be rich." - Cody D.

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JimHelms
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Re: Modem Disconnecting

Post by JimHelms » Thu Apr 19, 2018 7:55 am

Brady_ls wrote:
Wed Apr 18, 2018 9:46 pm
Modem> Network Status> General Information> Modem jumps between "Sierra Wireless, Incorporated MC7455" and "no modem present."

"Does no modem present" refer to communication between the router and the card?
This is normal behavior when Connection Monitoring is enabled with Modem Reconnect, and the modem cannot stay connected to the network and/or its pings returned. When this happens, the modem is rebooted and will not be detected during the process.

Compare your logs to the image I posted earlier. Your issue also appears to be antenna/connector/signal related.

k9kfx
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Re: Modem Disconnecting

Post by k9kfx » Fri May 18, 2018 5:50 pm

Same problem I have on sprint with the same setup. Apparently you have to have advisability perfect signal with a perfect 20 sinr to stand a chance. T-mob sim in exact same setup with worse signal and I get 2 bands 20mhz no disconnects for 2 days now. Hmmm.

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JimHelms
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Re: Modem Disconnecting

Post by JimHelms » Sun May 20, 2018 8:16 am

Same problem I have on sprint with the same setup. Apparently you have to have advisability perfect signal with a perfect 20 sinr to stand a chance.
A perfect SINR of 20 is not required. But it must be within acceptable levels to maintain a connection.
RSRQ (dB): -14.8
SINR (dB): -2.6
RSRQ (dB): -15.6
SINR (dB): -1.6
These reading are well below acceptable levels. Compare these readings to the chart below:


Signal Readings.png

Have you tried relocating the router to a different location in an attempt to approve the signal?
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ph34rful
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Re: Modem Disconnecting

Post by ph34rful » Mon Sep 03, 2018 9:25 pm

Did any of you guys ever resolve this issue or at least figure out what was causing it? I'm having pretty much the same issue with a EM7455 in a USB enclosure and a Golden Orb flashed router. The blue light on the USB enclosure turns off when I experience the disconnects which I'm guessing indicates a power related issue that is most likely the result of poor signal quality, or some combination of both. Haven't really been able to make any headway on resolving the issue as the device is at a distant relative's home which makes troubleshooting very difficult, if not impossible.

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JimHelms
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Re: Modem Disconnecting

Post by JimHelms » Wed Sep 05, 2018 5:11 pm

ph34rful wrote:
Mon Sep 03, 2018 9:25 pm
Did any of you guys ever resolve this issue or at least figure out what was causing it? I'm having pretty much the same issue with a EM7455 in a USB enclosure and a Golden Orb flashed router. The blue light on the USB enclosure turns off when I experience the disconnects which I'm guessing indicates a power related issue that is most likely the result of poor signal quality, or some combination of both.
I assume you are using a quality USB power cable that attaches the USB modem enclosure to router. Using the stock cable or even a bad or faulty cable will cause disconnects. A lot of the USB power cables (including the one that come with the enclosures) will not carry the current necessary to power most higher category modems like Sierra EM7455. This possibility should not be over looked. And, it is one of the easiest fixes.

Other food for thought:

It may also help to disable Connection Monitoring until you get a stable connection. Some prefer not to run it at all.

The connection monitor pings an ip address (i.e., 8.8.8.8...) every X seconds, and if the ping fails Y number of times within Z seconds/minutes, it considers the internet connection is down and reboots the modem in an attempt to help it reconnect. This results in the enclosure's lights going off (as you mention above) while the modem reboots.

Thus, it is not hard to imagine how a modem can get stuck in an endless loop of rebooting.

If a modem struggles to maintain a connection due to inadequate signal strengths, it may be best not to use Connection Monitoring, or at least configured to be very tolerant to a number of failed pings before it decides to take action and reboot the modem--which is often a necessary step to reconnect a modem to the network.

The connection monitor's pings may prevent an idle modem (i.e., inactive, no data transferred) from being disconnected/booted from the network as an inactive device. The ping is thought to help keep the connection alive.

Also, since you are using an USB adapter enclosure behind a router, you may want to try setting Connection Monitor to Enable on Power Toggle or Modem Reconnect.

Of course, the proper functioning of any cellular modem depends on its access to adequate "usable" cellular signals.

Haven't really been able to make any headway on resolving the issue as the device is at a distant relative's home which makes troubleshooting very difficult, if not impossible.
Yes, that would make it tough.

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