3.2.7 Case study: debugging a web load error >>> Web page load errors >>> How Computers Work
If a different device on the same network works properly, it is a strong sign that it could be a problem with your computer.
If the problem is with your computer, your phone should work fine.
Checking a device on a different network is a great way of seeing whether the problem is with the network.
This is the best sign that it is a login problem. Most well-designed sites will show a login page, but I’ve see lots of situations where it shows the wrong page but doesn’t make it clear that you are not logged in.
A log in problem won’t affect other sites (but it might affect other pages on the same site).
If the problem is with the server it won’t affect other sites (but it will affect other pages on the same site).