Why am I unable to associate an Elastic IP to an EC2 instance in a second VPC on AWS?

Question

I have for a long time a VPC (with 1 subnet) on Amazon Web Services (AWS) with several instances each having an Elastic IP address.

For new needs, I have defined a second VPC (with 1 subnet also) on my same account: for some reasons, I can't associate EIP (which is allocated with no problem) to instances launched in VPC #2: the interactive wizard of the console only presents me the instances of the first VPC.

Is it a known limitation or am I doing something wrong?

Answer 1

Two questions:

1. How many EIP's do you have on your account?

2. Is the 2nd VPC using a NAT instance to access the Internet?

EIP addresses should only be used on instances in subnets configured to route their traffic directly to the Internet Gateway. EIPs cannot be used on instances in subnets configured to use a NAT instance to access the Internet. (aws.amazon.com)