Interface eth1 doesn't work with IPv6

[Raid]

We tried to use CentOS7.6 as the main OS for our work with IPv6 enabled.

eth0 is configured properly with IPv6 and it's accessible from port 80, however eth1 seems to be working with IPv4 only not 6

What is the proper configuration to setup IPv6 for two or more ENI, I'm using AWS.

The Amazon AMI image using a tool during lunch called ec2-net-utils

Configuring Your Network Interface Using ec2-net-utils

Amazon Linux AMIs may contain additional scripts installed by AWS, known as ec2-net-utils. These scripts optionally automate the configuration of your network interfaces. These scripts are available for Amazon Linux only.

I used this image and it's working for both ENI and both IP protocol. what is the way with CentOS 7.6 with (cloudinit)

Also I'm not sure who to contact at this point, CentOS for the networking or AWS for what is the right IPv6 default gateway to use.

[aks]

So the way AWS works, it tends to not get in the way (too much). But it can - and it's only fairly a recent addition to AWS (!)

If you have a valid IPv6 address from the machine you are sending (outbound/originating) and there is a valid IPv6 address on the reciver (inbound/listener) and the DNS (or other naming services) works, then it MUST be the network between.

Also revisit what you done, and question each step. It's easy to come to a false conclusion.

At home, I've been using IPv6 since 2014 (when my ISP started to allow it). 100% of the times I've used it, I can get to IPv6 only nodes.

The Linux implementation is quite good actually (bar all the politics and security issues from those politics).