AWS lightsail ubuntu SSL issue and 404 error

In this case, WordPress was installed using Ubuntu on Amazon Lightsail.

After installing and setting up and writing, there were no SSL-related issues, so I installed it by running a command in Linux itself. A 404 error occurred as shown below.

It was like this, so I looked for it and found that there was an error exclusion process like this, so I tried it.

https://thekkom.tistory.com/122

ubuntu:: Excluding repository error items when apt-update ERROR MESSAGE E: The repository 'https://ppa.launchpadcontent.net/bashtop-monitor/bashtop/ubuntu jammy Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user...

thekkom.tistory.com

I tried again, but when I checked, it showed a DNS error.

I would like to ask where I set DNS errors. sob

Where can I check that part? I'm thinking about contacting Amazon about DNS.