GL-X750 AT Commands fail

Hello community,

I was attempting to setup a Verizon MVNO SIM in my Spitz this evening and ended up jacking up the modem configuration. Somehow I got the modem to show up under both 3G/4G modem and USB Tethering? Anyways I ended up factory resetting the device and the modem still shows up under USB Tethering. So I’m trying to wipe the modem configuration and when I issue the command (AT+QPRTPARA=3) I get an error message on /dev/ttyUSB0 or /dev/ttyUSB1 of “ERROR: Failed to Execute Command”

Hoping the community here has some ideas on how I can factory reset the modem?

Can you show me a screenshot of that? Never saw that it appear as tethering.

The interface for AT command is ttyUSB2, not ttyUSB0 or ttyUSB1

When trying to run AT commands on the modem the only options I get are either ttyUSB0 or ttyUSB1. I have attached several screenshots via multiple posts.

Here is the list of AT commands that I ran that appeared to have caused this issue:


Cannot believe it. Very strange.

Any suggestions on what I could do to fix the issue?

Just some more information about what happened. It appears I changed the configuration mode from QMI (Default) to ECM by issuing AT command “AT+QCFG=“usbnet”,1”. I cannot seem to figure out how to issue AT commands to the modem to set it back into QMI mode.

From Quectel EC25 4G modem QMI mode - #3 by idarlund - Hardware Questions and Recommendations - OpenWrt Forum

AT+QCFG="usbnet",0 - is PPP & QMI (default)
AT+QCFG="usbnet",1 - is ECM.
AT+QCFG="usbnet",2 - is MBIM

Can you try?

I would love too, except I can’t seem to issue any AT commands to the modem. I even installed socat and try issuing the commands against ttyUSB2 and the device isn’t responsive.

You didn’t mention your model so I tried my, XE300 with EP06ELAR03A08M4G.

Step 1: Changing to ECM mode.

I issued AT+QCFG="usbnet",1 and then did a modem reset from the UI, then the modme goes to ECM mode.

I still can see ttyUSB1 to ttyUSB3. This may be different from X750 because XE300 has 1 more ttyUSB.
I cannot connect in the modem section

I can usb0 in tethering section and I just click connect and it works.


I issued AT+QPRTPARA=3 and the modem respond OK. Then I did a modem reset. The status is still the same as in Step 2.

I think this command does not work at all. Maybe this is related to modem’s firmware version as well.

Step 3: AT+QCFG=“usbnet”,0

I issued AT+QCFG="usbnet",0 and got “OK”. Then did a modem reset from the UI.
The modem goes back to original mode.

I have the GL-X750v2 with a EC25-AF modem. It won’t issue any commands on the modem I either get a busy message or another message I forget. Doesn’t matter if I try issuing the commands on ttyUSB1 or tryUSB2.

Then seems nothing could be done now.

So I assume you believe the modem is bricked and will need to be replaced?

Yes. It may be just easier to replace the modem than indepth debrick.