Custom network configuration gets overwritten

I was forced to modify the interfaces configuration (/etc/config/network) to add a vlan tag to my wan interface (eth0). This is required as the DSL provider I use requires VLAN tag for dialing PPoE connections via the DSL modem. Unfortunately setting a VLAN tag on a interface is not possible via the webinterface. So I edited it manually and added this to my “wan” interface like this (eth0.40).

config interface 'wan'
	option hostname 'office360'
	option metric '10'
	option username '<username>'
	option password '<password>'
	option disabled '0'
	option proto 'pppoe'
	option ifname 'eth0.40'
	option ipv6 '0'

Once I did this and restarted my GL-MiFi (v3.203) everything works fine. The WAN DSL connection (cable) connects fine.
However: from time to time (maybe on connection reset of the provider?) the whole network interface configuration is completely rewritten and my changes (adding the VLAN40 via eth0.40) is completely reverted.
Does the firmware have a functionality to periodically overwrite /etc/config/network ? If yes, how can I prevent this? Where does the default configuration come from?


The firmware should not modify your config. But did you change the config via the Interface? If you did, the Interface may call API to change your config to the default one.

I did not access the UI configuration or change anything after the manual change on the shell.
The router was just sitting there for several days and when I checked back the config was gone…

I did revert to the working config, rebooted and now will leave the MiFi untouched, lets see what happens.

I thought maybe it has to do something with overlayfs but since the last change also survived a reboot…