Why is there no connection to some services/sites?

Question

Computer networks

Suddenly stopped showing the player on Twitch.Tv. Flash Player is installed, but I decided to try to update Adobe Flash Player. It also doesn't load. I play Gwent, the site gog.com also does not load, the launcher, respectively, too.
YouTube and other sites work as they should.

Screenshots

I tried to use a VPN, and the sites start to open and work.
I even downloaded Adobe Flash Player through VPN, but it is not installed - there is no connection.
I did not do any manipulations with the network. I played Gwent and watched Twitch this morning.
Win 8.1 Internet connection via WiFi

Answer 1

90% problem with mtu. Smoke how to set it up on a laptop or wifi router

Answer 2

Try to access the site by ip, maybe it's dns