The reason you see this error is, one file uses multiple URLs to load. This will have a negative effect on your website, and make pages load slower.
Fix Serve Resources from a Consistent URL
As mentioned above, serve resources from a consistent URL error occurs when you are calling a file with multiple URLs.
For example, imagine two totally unrelated plugins use the same font on your WordPress website. Each of them will send separate requests to use that particular font and this will bring unnecessary traffic to your HTTP and as a result, your website will load slower.
To fix this issue, you must check the code used in your plugins, themes and also URLs used in your website. You must be patient and check every URL one by one.
If you see two different URLs for one file, delete one of them instantly. They may be for Js files, images or even CSS files. Our goal is to delete unnecessary URLs requesting one file from the server.
By doing so, your website’s speed will improve dramatically. Also, don’t forget that your website’s speed depends on other factors as well. For example, your website’s structure, programming type, hosting provider and etc.
How to fix serve resources from a consistent URL?
As we discussed above, this warning occurs in GTmetrix recommendation when you call identical resources like images, js or css files with different URLs.
You can fix this easily, if you see different URLs for the same resources (images, js, css) then delete one of the urls immediately. It will automatically help to reduce requests and improve site speed as requests are generated due to file duplication and will minimize after deletion of the same url which was used for several times.
If you are using the same resources in multiple subdomains or linked sites then inconsistent URLS will create there.
For example, your main website (ext: mbaz.net), subsite is sub.mbaz.net shares an image with subsite then this will create two paths for the same resources.
To fix the issue, serve the resource from a single hostname, rather than facilitating it from a similar site and its region. That is, there is a need to have it on. To outline, mbaz.net connection to it from sub.mbaz.net.