Issues with new EM20-G

[prideauxx]

Hello,

I'm attempting to configure a Quectel EM20-G for my setup, and have run into a dead end. Specifically, commands that persist on my EM12-G (such as disabling roaming) do not persist across a reboot on the EM20-G.

Specifics: I initiate a query command for roaming: AT+QCFG="roamservice". The result is 255 (roaming: AUTO). I then execute an AT+QCFG="roamservice",1 command to disable roaming. I then query the command again AT+QCFG="roamservice". The result is 1 (roaming: disabled). I then reboot the router. After rebooting the router, I initiate another command for roaming: AT+QCFG="roamservice". The result is back to 255 (roaming: AUTO).

If there is something I am missing specific to this modem's setup (ex: manually enabling nvram save), I'd love to hear it.

Thanks!

[prideauxx]

Update:

No luck whatsover, sadly. It may be a malfunctioning unit. No nvram setting will persist past a reboot. I've been working with BillA to try a number of different approaches, including reverting the firmware to a previous version using a M.2 to USB adapter and a Windows box. No joy. The older firmware acts just the same as the newer regarding inability to persist settings.

Additionally, using the M.2 to USB adapter and an AT command interface, I attempted to set and persist the aforementioned roaming disable command from the Windows box. No dice, but was at least able to remove the router device (WG3526) as a potential culprit.

Hopefully I can work with the merchant I bought this from and get an working unit soon.

[Yipzy]

Update:

No luck whatsover, sadly. It may be a malfunctioning unit. No nvram setting will persist past a reboot. I've been working with BillA to try a number of different approaches, including reverting the firmware to a previous version using a M.2 to USB adapter and a Windows box. No joy. The older firmware acts just the same as the newer regarding inability to persist settings.

Have you tried to use it as a startup AT command in ROOTer? IIRC there is a setting specifically for it.

[prideauxx]

Have you tried to use it as a startup AT command in ROOTer? IIRC there is a setting specifically for it.

I'd like to see where that may be--could be useful for future experimentation. I was exploring the WG3526's Linux filesystem via terminal connection (ssh), and grepping for "AT+" commands to see areas where modem setup was occurring. Main area of interest seemed to be under the /usr dir, but I digress.

Many thanks to Didneywhorl for saving my bacon on the modem issue. But first a warning--This applies only for the Quectel EM20-G (has not been verified for anything else), and honestly shouldn't be done (unless it needs to be done).

Because of [reasons], I had factory reset my modem, an EM20-G, using the 'AT+QPRTPARA=3' command. This really shouldn't be done, as it puts wear/strain on the physical nvram components and will prematurely lead to hardware failure if overused--you've been warned. This may have led to a side-effect in which I could not save/persist any values whatsoever on the modem (on reboot, all set values would revert).

The fix? It would appear this is my situation for this specific device from here on out: After I set a value I need to be persisted across reboots (say, disabling roaming), I now need to enter the following command last: 'AT+QPRTPARA=1'. Through my testing this morning, for my specific case and condition, this must be done now, regardless of how things *should* work. YMMV.

NOTE: This is being shared to help others in a similar situation. Please, as others wiser than me have stated repeatedly in the past, blind use of AT+ commands can cause significant, irreparable damage to your modem. And in the end, it's your own fault (not a manufacturing defect). Research, research, ask questions, and be patient before trying something that may cause harm to your investment!

[prideauxx]

To further the discussion (and attempt to make sense of things) I did some digging:

atqprtpara_modem_cmd.jpeg

(source: https://wenku.baidu.com/view/58f3d4b919 ... 9a55b.html)

[Didneywhorl]

AT+QPRTPARA=1 will save your settings. I always recommend it after resetting the modem. I think we emailed about this. Im tired and don't remember