Hi ! Recently I bought a Cirrus Router, I want to know if theres a way to using as a bridge (not wifi bridge) (maybe AP ?) and keep the 4G LTE backup if the wan fails, am asking this because It use other ip’s that my main router and I want to include the Cirrus to the main ip’s but keeping the 4g backup to an specific devices that use the Cirrus Lan port. It is possible? 
This may be possible, but very complicated.
It will break the current multi-wan failsafe settings. You may also need to write some scripts to do this.