AWS VPC Fargate Connectivity Fix

I need immediate expertise to resolve load balancer connectivity issues with my AWS VPC Fargate containers inside a private subnet. The containers are not accessible from the internet-facing load balancer, and while I have configured the security groups, I can't seem to solve the problem. This is for the dev account, prod account works fine. The original consultants who did it are not available.

Ideal skills and experience:
- Mastery of AWS VPC and Fargate
- In-depth knowledge of load balancer connectivity
- Experience with security groups and networking configurations