How to capture client information in a application behind AWS load balancer

Question

Running a [FIX][1] server behind a AWS load balancer, The Load balancer is located outside the application VPC.

Need to allow/dissalow connections based on client IP.

As client connection are through load balancer, only the load balancer IP is visible to the application. In order to get the client IP have tried below options,

1. Enable IP preservation in load the balancer
2. Enable proxy protocol in the load balancer

#1 didn't work as the load balancer is outside the application VPC. #2 Able to deliver the IP information but it requires application support.

Is there any other options available?

if not, how can i support proxy protocol for Java FIX application (written using qucikfixj)

[1]: https://www.onixs.biz/fix-protocol.html#:~:text=The%20Financial%20Information%20eXchange%20(FIX,entities%20including%20trade%20allocation%2C%20order