Not sure how many here touch wordpress, but I have a test server running the latest wp, 5.5. Server is rhel 8 for wp, and I have a separate rhel 8 server for the mysql db.
Now, I can get through the setup and log into the admin console.
My issue is when I try to set the URLs for it.
Changing either/both of the ULRs causes the site to be unreachable.
Only thing I can think of is that I have not set up a vhost at all, and maybe that is the problem.

But I am wondering if anyone knows more about this issue?
I am also on the wp forums, but they are not heavily populated.

If you set incorrect URLs, the site doesn't work.

If the site used to work, why do you need to set the URLs? What do you set them to?

What are the URLs and ip addresses in question?

This is a shot in the dark, but in general, if you are going to use URLs, as opposed to ip addresses, you need some sort of DNS service to translate the URLs into ip addresses. It can be a local DNS or even hosts files for a local connection, but you still need something to translate the ip address into the URL.

I had also thought of dns, I will have to check into that.

I am going to be running multiple sites on 1 server, and they will be world accessible. This is also a replacement server, so I'd like to keep the same URLs. Right now, I am just trying to get a wordpress test fully functional.

As frankbell said, you will need to setup something to translate URLs to the server IP addresses.

But the site URLs are also managed within WordPress. I don't recall exactly where, but when changing a test site to a live site -- from testsite.com to livesite.com for example, we had to also change the base URL setting in the site configuration. wordpress.org documentation is your friend.

Bringing this back up, as I know a bit more about wp now.

So, still rhel 8, latest wp, but I doubt that matters much.

This will still be a replacement server, eventually.
So, I can get wp installed, and do multiple installs. These installs all work at first, before I touch anything for a vhost file.
So, ip/install name such as wptest/1/2.
So, I get through that and I can install plugins, ect.

Now, since multiple sites will run on 1 server, I need a vhost.conf and ssl. conf. Well, I think I need the ssl.conf, I installed the mod_ssl.
My work has internal dns, and that is all I am using for now. The world dns can wait for now.
So, I set a cname for both test installs, wptest and wptest2. I set up a vhost file with an entry for both sites. They are identical aside from of course the name, a 2 added, and the document root location.
Restart httpd, of course.
When I put in the first name, page comes up fine. Second name, not so much.
URL not found, and it shows the IP of the server and directory root.

I've tried to look at the current server, but it only provides part of the picture.

Ideas are welcome, as are sites that might describe a comprehensive setup.
Thanks!