Domain and dns

[iPujhin]

hello sir,
I have this problem, can you help me? I created a service in AWS and released ports 80,443,53,51820,22. my free domain is from duckdns, I already indicated my IP but even so, during installation, the following error message appears: DNS problem: SERVFAIL looking for CAA for deviceconnectionvpn.duckdns.org - the domain nameservers may be faulty

[EdmundDuckDuck]

I think I have the same problem here and I guess there is no program running that listens to port 80, so we get an error.
Should there be a program started ( vpn ) before adding the duckdomain?
How can it be started manually or must we test with a webserver like apache?

[EdmundDuckDuck]

I tried apache to see if my IP / duckdomain worked and it does.
Starting the script again resulted in an error that port 80 was already used by another program ( apache)
Any trouble shooting suggestions are much appreciated