selection of SSL VPN listening interface

I have Sophos XG210 (SFOS 17.1.3 MR-3) with WAN1 and WAN2 interfaces. Both WAN1 and WAN2 belong to zone WAN. WAN1  is much faster then WAN2 and I'd like to know if there's any way to force SSL VPN users go through WAN1 only when accessing our internal resorces without dropping packets for WAN2?