A BIG-IP has two load balancing virtual servers at 150.150.10.10:80 and 150.150.10.10:443. The port 80 virtual server has SNAT automap configured. There is also a SNAT configured at 150.150.10.11 set

The original client IP is only preserved when no applicable SNAT exists, but the standalone SNAT explicitly covers the 200.200.1.0/24 source range and overrides pass-through behavior.

The standalone SNAT object is configured to translate traffic from the 200.200.1.0/24 range to the address 150.150.10.11. Since the client IP 200.200.1.1 falls within that range, BIG-IP applies this SNAT when the packet is forwarded to the pool member. The port 443 virtual server has no SNAT of its own, so the matching standalone SNAT is applied independently of the virtual server configuration.

The floating self-IP on the egress VLAN is the translation address used by SNAT automap, which is configured only on the port 80 virtual server, not on the port 443 virtual server handling this HTTPS request.

BIG-IP does not use the ingress VLAN's floating self-IP as a SNAT translation address under any standard configuration; SNAT automap always selects from self-IPs on the egress VLAN.