willymilkytron:

== Device problem occurs on

Any device using 3g usb modems

== Steps to reproduce

My modem not works after reboot, in LuCI i get "Error: Network device is not present"
In logs:

Sat Jan 25 23:00:37 2020 daemon.notice netifd: Interface 'ppp0' is setting up now
Sat Jan 25 23:00:40 2020 daemon.notice netifd: Interface 'ppp0' is now down

When i click "restart" on ppp0 - nothing happens and no any logs in logread.

But all needed ttyUSB's exists:

root@OpenWrt:~# ls /dev/ttyUSB*
/dev/ttyUSB0 /dev/ttyUSB1 /dev/ttyUSB2 /dev/ttyUSB3

== Software versions

OpenWRT 19.07

== Fix

The problem has already been reported multiple times on GitHub

#2351
#2359
#2716

Fix is already on master, please backport to 19.07: 4821ff0