I am having thw same issues, but it is only happening on 1 computer out of 3 on my network, doesn't matter if its wifi or wired.
When I use Netflix on my ethernet-connected PC, I have to sign in with a username/password. Are you using the correct one for the one computer?
Its happening to other web sites too. It takes almost five minutes to get to speedtest website and then is gets bogged down and won't do anything.