Are you stretching the usefulness of your old intel mac running el cap (or earlier) and all of the sudden right in the middle of nailing down your term paper and wikipedia decides not to connect (or a whole helluva lot of websites for that matter)? All your common browsers are complaining and boo-hoo ing like GRUMPY PRINTER. Rest assured, you're not stuck. There's an incredibly simple and calming fix. This video does a fantastic job of explaining it.
The short story is download certificate ISRG Root X1 (the PEM variant) from THIS safe website and run it. It will install this to your keychain, where under certificates you'll most likely see it with a big red X. Double click this, tell keychain to "Always Trust" and then drag to System so it is utilized across the entire system.
Go back to wikipedia and you should be good to go, crisis averted. Bookmark the website for good measure for future updating.
The short story is download certificate ISRG Root X1 (the PEM variant) from THIS safe website and run it. It will install this to your keychain, where under certificates you'll most likely see it with a big red X. Double click this, tell keychain to "Always Trust" and then drag to System so it is utilized across the entire system.
Go back to wikipedia and you should be good to go, crisis averted. Bookmark the website for good measure for future updating.