dynamic default options can not be changed once interface is up using proto=wwan

[LEDE Bugs]

Hi,

I refer to this bug that I have opened

https://bugs.lede-project.org/index.php?do=details&task_id=625

The basic problem here is once the WWAN interface is up, you can not
change dynamic defaults anymore if proto=wwan (so for mobile broadband
devices).

Easy test is, configure a device as follows

uci set network.wwan=interface
uci set network.wwan.proto=wwan
uci set network.wwan.defaultroute='0'
uci set network.wwan.pincode=****
uci set network.wwan.metric=10
uci set network.wwan.apn=****
uci commit && /etc/init.d/network restart

Now try to change metric or default route and just "reload" network.
You will see that it does not have an affect at all. I have added a
couple of echos to netifd-proto.sh as well as to proto/qmi.sh and
proto/wwan.sh. Unfortunately I see no echo at all printed !

But if i use qmi as proto directly, everything works. Proto and metric
are changed on network reload. I have to fix this issue by mself.
Unfortunately I currently have no idea what to do next, what the cause
could be. Main question to me is who calls qmi.sh, wwan.sh ....

It would be great if someone can give me a hint

Regards,
Andreas