Why won't my MInecraft connect to servers?

Yesterday my Minecraft stopped wanting to connect to any servers. It was working but I went to connect and it would try to connect then the red words "Can't connect to server" appears under it. I reset the router, restarted my computer, reinstalled Minecraft. None of these fixed it. I logged out and logged back in and that worked. It's the connecting to the server that doesn't work. Can someone help me with this?

Added (1). Shamon, I have the new MacBook Air with 4GB of ram. Not a beast but is the best computer I own. It was connecting to servers two days ago, but yesterday it stopped.

Doctor, would all the servers be down? I tried connecting to my own self-hosted server and it wouldn't do that either.

Your computer is most likely not made for gaming. Do some research and find the one that has the right things for gaming.

The server is probably down