I am totally disgusted with Firefox because it constantly tells me it can't find a website when it was just at the very same website 5 minutes ago! I've tried you suggestions but they never work. My only solution is to restart my computer. I'm running macOS version 15.7 with the latest updates but this problem has been true for the last several versions of MacOS so I don't think that's the problem. Is there anyway you can resolve this problem. If you can't fix it, I'm going to have to switch to Safari.
Next time it happens, try opening that and some other sites with a different browser. If you can't then it's a PC/router/internet connections problem, not FF.
