bad gsm connections


I would appreciate advices how to cope bad gsm connections with NM. I do have auto set-up for gsm configuration.
Modem gets huawei_cdc_ncm and NM brings up WWAN0 interface. What I can see from systemd journal is that NM tries to keep connection by unplugging and plugging kernel driver (or somthing like that as "USB Mass Storage device detected", gets enumerated and drivers registered...).

Somehow this does not always work well enough, and connection does not recover before this embedded Linux card boots up.
I do also have connection monitor that tries to ping external server and it power sequences modem if PING does not succeed and eventually, if this lasts long enough also boots the card. Somehow, this sounds as overkill to have two processes executing virtually the same process. I tried to probe if NM did also power sequencing, but I could not detect that. However, I did find that discusses the very thing. I checked my kernel configuration and it turned out that rfkill was not enabled.

Is NM executing "wwan off" at the moments it unplugs kernel driver (or what looks me to unplugging it) so that I could drop that feature from connection monitor - provided that rfkill really touches usb power? Kernel do already have some services for usb power hanling in sysfs that my connection monitor uses for this power sequencing.


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