Yeah, so online it’s being mentioned that potentially it’s a problem with date and time not being set correctly (maybe confirm your time zone, and auto-set date and time), as SSL certs are time sensitive; also, check if you have any vpn or similar software installed which may perform web inspections. So, problems with the target websites certificate are ruled out, right?
also, your phone does not have those same issues which your MacBook has? are you usually using cell phone data as well, or just now as your MacBook has no internet whatsoever? If you don’t use it all the time, do you connect your phone to WiFi ordinarily? Sorry for all those questions, just trying to clear some stuff up. If you don’t answer, I’ll assume the problem was with the router and has been resolved by your company.