I'm trying to setup failover internet connection with the LTE modem, plugged into an OpenWRT rotuer (actually, I'm planning to try it in a couple of months, when get closer to it).

In order to reduce mobile traffic consumption, I'd like to keep modem's interface (wanb) down and bring it up only if the main WAN interface looses connection, like here: https://blog.ronsonchan.com/openwrt-failover-with-mwan3/ (MWAN3 notification script calls ifdown wanb if main WAN is connected)

Is it possible with the mini-mwan?