> If the maximum transmission unit (MTU) between hosts in your subnets is different, or your instances communicate with peers over the internet, you must add the following network ACL rule, both inbound and outbound.
If your instances communicate with peers over the internet. So by default, AWS was built to assume your instances do not communicate over the internet, lol.
https://docs.aws.amazon.com/vpc/latest/userguide/vpc-network...
If your instances communicate with peers over the internet. So by default, AWS was built to assume your instances do not communicate over the internet, lol.