Any way to set up wan as fail-over backup?

Hello

My query is simple...

I am using 3g for my primary internet connection on tomato and i would like to know if there is any way i could configure it so that if for some reason my 3g or 4g fails, tomato automatically switches over to wan and vice-versa for stable internet connection. Is this possible? Is there such a feature in tomato?

What am asking for is a feature which prioritizes connection source... 3g/4g >> wan(dhcp)

Regards!!