Lambda triggered by a custom resource works without a VPC but inside the VPC the lambda gets Timeout

Question

I have created a lambda that has to be triggered by a custom resource. Now when I test the lambda without putting it inside a VPC it works fine but whenever I put it inside a VPC the lambda does a timeout and the response is not sent back to the custom resource and the custom resource stack gets stuck on create in progress.

PS Although when I put the lambda inside a VPC i put it inside public subnets.

Need help

I have created a lambda that has to be triggered by a custom resource. Now when I test the lambda without puttuing it inside a VPC it works fine but whenever I put it inside a VPC the lambda does a timeout and the response is not sent back to the custom resource and the custom resource stack gets stuck on create in progress.

PS Although when I put the lambda inside a VPC i put it inside public subnets.