Running CiviCRM 5.11 plugin on WordPress. This is a fresh install on DigitalOcean.
In the WordPress Settings>General, there is a place to specify a URL, which I did using the URL for the website as registered in DNS.
When I first installed this, the setting used the IP address of the server, for example http://nnn.nn.nnn.nnn
With this setting, no problems.
After I was sure my DNS was pointing to this IP address and that it had propagated, I changed the setting to use the correct URL.
I can log in to WordPress okay but, when I click on the link to CiviCRM, I get a pop-up that says "Network Error: Unable to reach the server. Please refresh the page in your browser and try again. I do that and have to log in again.
All of the WordPress links are working fine. It only is a problem when I click on CiviCRM.
I changed it back to the IP address and CiviCRM works fine