All requests are being presented as if coming from ELB (loadbalancer) IP. That’s why too many requests error.
You can set the load balancer to forward the correct IP address with requests and that’ll sort the issue generally it is the X-FORWARDED-FOR Header that’s required here.
More details here:
https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/x-forwarded-headers.html