Minecraft launcher says "make sure you are online and try again" when attemping to log in

the version is irrelevant, I can't log in to my mojang account from the launcher at all. originally I could play the game, only offline, but having logged out that's not possible and I still have the same issue. I've tried restarting my router, restarting my computer, reinstalling java, and ensuring that java is allowed through the firewall.