SmallDragoon - 2017-09-20

Hello !
I used FWbuilder since a while with my basic needs and it is perfect.
I have now 2 different Internet connection available ( 1 ADSL, 1 4G ) and I would like to load balance traffic accross these 2 connections as well as a fail-over option.
I searched and found different topics / solutions which do not really looks reliable ( or outdated )
More reliable answers from my point of view are using tagging and classifications , but it is not clear for me how to proceed as well as if it is really the best / appropriate method to use ....
I would be interested by some suggestions / hints to move forward on my config
thanks in advance !