To which VLAN object belongs

Auto last hop always saves the inbound interface and src MAC from the packet. It doesn't matter what you have defined for IP's on VLANs.

BigIP also (Unless you disable it) insists on the outbound and return packets for outbound connections (bigip-server) coming over the same interface... And the client-VS connection is a separate connection from BigIP-Server. It's proxy. Whether you're translating the big-server connection IP's or not... Think of it as two connections and you'll have a better chance of understanding what it's all about.

H