I installed MediaWiki 1.35.1 onto an Apache server in XAMPP, with a port other than 80. The visual editor loads correctly, but when trying to save an edit it hangs then produces Error 28. This seems to be the same issue @CharlesCivi had in another posting. He mentioned he was able to add his "domain name to /etc/hosts using 127.0.0.1" but I am unsure of what exactly I should entering into the hosts as the domain... My server runs on "localhost:<port>/test-wiki/". I change localhost to a lan address for other machines, and then I change it again for my IP address when I need to access it outside the network...
Topic on Project:Support desk
I don't remember all of the details, but it's really dependent on the $wgServer entry in LocalSettings.php
Whatever you have in there, you need to be able to access it from the server, as if you're reaching it from the outside.
In my case, I'm using a domain name, so I added the loop-back IP, 127.0.0.1, to /etc/hosts with the domain name:
12.0.0.1 mydomain.com
This worked ok, but I didn't like it. Since I'm using AWS, I added security group entries for the server's own address on ports 80 and 443 and that worked as well.
It looks like you're using localhost, instead of a domain name. In that case, your /etc/hosts file should have this entry:
127.0.0.1 locahost