Connecting Lightsail to a subdomain using IPV6

Hello.

If you are able to access it normally, it may be something on the client side.
You may want to try the troubleshooting steps below and see if it helps.
https://www.partitionwizard.com/partitionmanager/err-address-unreachable.html

I am having the same issue. I took a snapshot of my old lightsail CentOS 7 instance and created a new instance with this snapshot choosing dual IPv4 and IPv6 instance. I am able to connect with IPv4 address but has not been able to connect with IPv6 address. I tried with PuTTY, FileZilla and through browser, nothing is working with IPv6 address. I tried for two full days. I then created a subdomain pointing to IPv6 address to see if this works. I used subdomain name instead of IPv6 address in PuTTY and FileZilla. It didn't work. Then suddenly it worked with subdomain name. I got connected to server using both PuTTY and FileZilla. I got exited that it is working (i thought it might have been DNS propagation issue). Again I tried after a few minutes with subdomain to test, and it is not connecting. I don't what's going on. I am getting connection timed out error all the time. My same firewall ports are open for both IPv4 and IPv6. I have no answer.