F5 Virtual Server responds to clients with pool member port instead of VS port

I have an F5 HA cluster deployed in one-arm mode with SNAT and source port preserve enabled (by default since i used iApp templates). The VS is configured to listen on port 443 with an http to https redirect enabled. Challenge is we have noticed that for pool members listening on different ports other than port 80 eg port 9080, when the traffic is sent to such pool members the response to the client goes with the pool member port thus the web page doesn't load since the firewall permits only ports 80 and 443 for client to F5 VS communication. Expectation was that response to clients should be strictly on port 443.