GL-X750 won't connect to Verizon anymore

I had good success with this device for the first couple of months that I had it and then it suddenly stopped connecting to the Verizon network. I am using the same sim card since the beginning. That sim card still works in my Jetpack without any issue.

Currently, I see an error on the main page saying “SIM card not registered”.

Following is the system log:

Thu Oct 1 20:58:04 2020 daemon.notice netifd: Interface ‘modem_1_1_2’ is setting up now
Thu Oct 1 20:58:06 2020 daemon.notice netifd: modem_1_1_2 (5456): cat: can’t open >’/tmp/modem.1-1.2/signal’: No such file or directory
Thu Oct 1 20:58:06 2020 daemon.notice pppd[5568]: pppd 2.4.7 started by root, uid 0
Thu Oct 1 20:58:07 2020 local2.info chat[5657]: abort on (BUSY)
Thu Oct 1 20:58:07 2020 local2.info chat[5657]: abort on (NO CARRIER)
Thu Oct 1 20:58:07 2020 local2.info chat[5657]: abort on (ERROR)
Thu Oct 1 20:58:07 2020 local2.info chat[5657]: report (CONNECT)
Thu Oct 1 20:58:07 2020 local2.info chat[5657]: timeout set to 10 seconds
Thu Oct 1 20:58:07 2020 local2.info chat[5657]: send (AT+CGDCONT=1,“IP”,“VZWINTERNET”^M)
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: timeout set to 30 seconds
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: expect (OK)
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: AT+CGDCONT=1,“IP”,“VZWINTERNET”^M^M
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: OK
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: – got it
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: send (ATD991#^M)
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: expect (CONNECT)
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: ^M
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: ATD
99
**1#^M^M
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: CONNECT
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: – got it
Thu Oct 1 20:58:08 2020 local2.info chat[5657]: send ( ^M)
Thu Oct 1 20:58:08 2020 daemon.info pppd[5568]: Serial connection established.
Thu Oct 1 20:58:08 2020 daemon.info pppd[5568]: Using interface 3g-modem_1_1_2
Thu Oct 1 20:58:08 2020 daemon.notice pppd[5568]: Connect: 3g-modem_1_1_2 <–> /dev/ttyUSB4
Thu Oct 1 20:58:08 2020 kern.info kernel: [ 3479.089372] 3g-modem_1_1_2: renamed from ppp0
Thu Oct 1 20:58:09 2020 daemon.notice pppd[5568]: Modem hangup
Thu Oct 1 20:58:09 2020 daemon.notice pppd[5568]: Connection terminated.
Thu Oct 1 20:58:10 2020 daemon.info pppd[5568]: Exit.
Thu Oct 1 20:58:10 2020 daemon.notice netifd: Interface ‘modem_1_1_2’ is now down

This text then repeats over and over.

I have tried resetting the device and looking for clues but at this point I am lost.

Are you using a SIM Adapter by any chance?

I am. I don’t have another one to troubleshoot with at the moment. Can they cause issues?

Yes, they can… you can try to remove/reseat the SIM card - there is a subtle difference on SIM’s with 2FF/3FF and the 4FF Nano SIM’s - the Nano SIM’s are thinner by about 0.1 mm… compare to 2FF (SIM) and 3FF (MicroSIM)

Why it is ttyUSB4? I remember it should be ttyUSB2 or ttyUSB3

Try putting a piece of clear(Scotch) tape on the top of the sim & adapter before you put it pack in.

This has been solved. I wasn’t able to get it working by shimming the sim so I got another sim from Verizon. That also didn’t make a difference.

I then reset my modem with

AT+QPRTPARA=3

and rebooted the device. It connected almost immediately and has been working fine for the last day.