Just adding my own experience here for the benefit of anyone hitting the same problem. After upgrading my Netgear WNDR3800 from OpenWrt 17.x to 19.07.3 I noticed that my 3G/4G/LTE modem Huawei E3276 would more often fail to come up on the wwan interface after reboot:
root@router:~# ifstatus wwan
{
"up": false,
"pending": false,
"available": false,
"autostart": true,
"dynamic": false,
"proto": "ncm",
"data": {
},
"errors": [
{
"subsystem": "interface",
"code": "NO_DEVICE"
}
]
}
The behaviour was random and on the next reboot the modem might come up.
This is what was printed in the system log when failing:
Sun Jul 19 12:08:33 2020 daemon.notice netifd: Interface 'wwan' is setting up now
Sun Jul 19 12:08:45 2020 daemon.notice netifd: wwan (1733): WARNING: Variable 'error' does not exist or is not an array/object
Sun Jul 19 12:08:45 2020 daemon.notice netifd: wwan (1733): Unsupported modem
Sun Jul 19 12:08:46 2020 daemon.notice netifd: wwan (2188): Stopping network wwan
Sun Jul 19 12:08:46 2020 daemon.notice netifd: wwan (2188): sending ->
Sun Jul 19 12:08:50 2020 daemon.notice netifd: Interface 'wwan' is now down
and this is most probably because of /lib/netifd/proto/ncm.sh getting an empty $manufacturer because of a too short $delay:
[ -n "$delay" ] && sleep "$delay"
manufacturer=`gcom -d "$device" -s /etc/gcom/getcardinfo.gcom | ...`
[ $? -ne 0 ] && {
...
}
json_load "$(cat /etc/gcom/ncm.json)"
json_select "$manufacturer"
[ $? -ne 0 ] && {
echo "Unsupported modem"
...
}
I experimented with different delays in /etc/config/network and I seem to get consistent successful reboots with a delay of 40 seconds for my hardware combination:
config interface 'wwan'
option proto 'ncm'
option ifname 'wwan0'
option device '/dev/cdc-wdm0'
...
option delay '40'
and this is what the system log looks like when successfully bringing up the wwan interface:
Sun Jul 19 12:08:33 2020 daemon.notice netifd: Interface 'wwan' is setting up now
Sun Jul 19 12:08:46 2020 daemon.notice netifd: wwan (1738): sending -> AT
Sun Jul 19 12:08:47 2020 daemon.notice netifd: wwan (1738): sending -> ATZ
Sun Jul 19 12:08:47 2020 daemon.notice netifd: wwan (1738): sending -> ATQ0
Sun Jul 19 12:08:48 2020 daemon.notice netifd: wwan (1738): sending -> ATV1
Sun Jul 19 12:08:48 2020 daemon.notice netifd: wwan (1738): sending -> ATE1
Sun Jul 19 12:08:49 2020 daemon.notice netifd: wwan (1738): sending -> ATS0=0
Sun Jul 19 12:08:50 2020 daemon.notice netifd: wwan (1738): sending -> AT+CGDCONT=1,"IP","---hiddenapn---"
Sun Jul 19 12:08:50 2020 daemon.notice netifd: wwan (1738): Configuring modem
Sun Jul 19 12:08:50 2020 daemon.notice netifd: wwan (1738): Setting mode
Sun Jul 19 12:08:51 2020 daemon.notice netifd: wwan (1738): sending -> AT^SYSCFGEX="02",3fffffff,2,4,7fffffffffffffff,,
Sun Jul 19 12:08:52 2020 daemon.notice netifd: wwan (1738): Starting network wwan
Sun Jul 19 12:08:52 2020 daemon.notice netifd: wwan (1738): Connecting modem
Sun Jul 19 12:08:52 2020 daemon.notice netifd: wwan (1738): sending -> AT^NDISDUP=1,1,"---hiddenapn---"
Sun Jul 19 12:08:53 2020 daemon.notice netifd: wwan (1738): Setting up wwan0
Sun Jul 19 12:08:53 2020 daemon.notice netifd: Interface 'wwan' is now up
Sun Jul 19 12:08:53 2020 daemon.notice netifd: Network device 'wwan0' link is up
Sun Jul 19 12:08:53 2020 daemon.notice netifd: Network alias 'wwan0' link is up
Sun Jul 19 12:08:53 2020 daemon.notice netifd: Interface 'wwan_4' is enabled
Sun Jul 19 12:08:53 2020 daemon.notice netifd: Interface 'wwan_4' has link connectivity
Sun Jul 19 12:08:53 2020 daemon.notice netifd: Interface 'wwan_4' is setting up now
Sun Jul 19 12:08:53 2020 user.notice firewall: Reloading firewall due to ifup of wwan (wwan0)
Previously I had the delay set to 5 seconds and at least weren't at that time aware of this problem so I encourage anyone seeing the NO_DEVICE / Unsupported modem error to experiment with longer delays in the interface settings.
(It seems at least one more person is having the same problem here)