If these four WAN connections are all on separate interfaces, you want Uplink Balancing with Multipath rules. First, make an Interface Group with WAN1& WAN2 and a second one with WAN3 & WAN4. Use Multipath rules to bind the desired traffic to each Interface Group.
Cheers - Bob
Sophos UTM Community Moderator Sophos Certified Architect - UTM Sophos Certified Engineer - XG Gold Solution Partner since 2005
