Internet connection with serial modem in oolite v1 (AR9331)

[jossvall]

Hello everyone,

Currently I have an Oolite v1 (AR9331) version of openwrt is 19.07.2.

I have a modem connected through an FTDI converter (TTL-USB), the modem works with AT commands. The router correctly turns the modem on and off by using GPIO pins (this is done with a small program I did), I have communication to the modem (I tested this using minicom).

What I want is to be able to use the modem as the WAN interface of the router, try to do it following the guide described in https://openwrt.org/docs/guide-user/network/wan/wwan/3gdongle but it does not work on my router.

This is the output of the logread command:

Tue May 26 23:23:45 2020 kern.err kernel: [ 1804.578557] ftdi_sio ttyUSB0: usb_serial_generic_read_bulk_callback - urb stopped: -32
Tue May 26 23:23:46 2020 local2.info chat[4359]: abort on (BUSY)
Tue May 26 23:23:46 2020 local2.info chat[4359]: abort on (NO CARRIER)
Tue May 26 23:23:46 2020 local2.info chat[4359]: abort on (ERROR)
Tue May 26 23:23:46 2020 local2.info chat[4359]: report (CONNECT)
Tue May 26 23:23:46 2020 local2.info chat[4359]: timeout set to 60 seconds
Tue May 26 23:23:46 2020 local2.info chat[4359]: send (AT&F^M)
Tue May 26 23:23:46 2020 local2.info chat[4359]: expect (OK)
Tue May 26 23:23:47 2020 kern.err kernel: [ 1806.488553] ftdi_sio ttyUSB0: usb_serial_generic_read_bulk_callback - urb stopped: -32
Tue May 26 23:24:46 2020 local2.info chat[4359]: alarm
Tue May 26 23:24:46 2020 local2.info chat[4359]: Failed
Tue May 26 23:24:46 2020 daemon.err pppd[4353]: Connect script failed

Does anyone have an idea what I am doing wrong?

[jossvall]

I already found the problem: the modem I am using does not have hardware flow, but by default the netfid configuration activates flow control.

flow control in /lib/netifd/proto/3g.sh was deactivated and now the modem manager controls the serial modem without problem.