Is it Hanging then loading?
Using Google’s public DNS isn’t that advisable unless done for a very specific reason so I wouldn’t bypass your ISP’s in your case.
Have you tried getting at it from a remote location or say gtmetrix.com (sign in for the uk test).
Have you tried speedtest.net for a general connection speed?
Have you tried via a wired network rather than wireless?
Have you got anything like a chromecast audio on your network?
Have you tried the classic off/on technical reset?
Have you tried another machine to replicate the issue?
100 questions sorry!
Edit – also tying via a VPN if you use one could be a good shout to help debug.
annnd – has the router taken a hammering over the last few days with new connections ect? or are you all using the internet when you don’t normally? You maybe overloading what the none commercial router can handle with concurrent connections.