Inbound Automous System IP hosted service inaccessible over secondary WAN link

We have the Peplink Balance 2500 setup as follows

         <img src="//" width="690" height="321"><br/>

Traffic inbound to our AS e.g ( through interface WAN1 ) for hosts natted directly on the firewall is fine.

However, traffic inbound on the WAN2 interface isn’t reaching the firewall.

I see we have responded with ticket 751560 and we can use that if there are additional questions on this design.