Hi all, After spending more time experimenting and trying to solve this problem, we have sort-of come to a conclusion. In case anyone else finds it interesting, I thought I should share it here. Our findings can be summarized as follows: - The problem is triggered by the switch from 3G to 2G. I can reliably trigger it by sending AT+ZSNT=1,0,0 to the modem or setting system selection to 0x0004 (both locking MF821D to 2G). - The root cause is the modem, but I can trigger the error on different USB hosts. I have been able to replicate it on the earlier mention router, my two laptops (with Intel-chipsets), a Raspberry Pi and some commercial mobile broadband routers. However, some hosts seem more resilliant than others. One for example the TP-Link I can trigger it all the time, while on my laptop it is more seldom. - One theory that we have not been able to verify is that the problem is somehow related to ISP. I got some friends in another country to try the AT-command with MF821D and the TP-Link WDR4300, and they did not see it. - I tried the same with another modem I have, the Huawei E392. I had no problems locking to 2G or moving between 3G/2G. - Our current work-around is to disable 2G. After doing this we have not seen this problem. -Kristian -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
