Possible reason: DNS hijacking of operator, or company internet limit.
It is recommended to switch to a reliable DNS, like Google DNS, OpenDNS and more.
How to do:
- Open Control Panel > Network and Internet > Change Adapter Settings, double click on your current network connection and then click Properties > “Internet Protocol (TCP/IPV6” and check to use the following DNS server location: 188.8.131.52 and 184.108.40.206;
- Press Win+R to open cmd, copy and paste ipconfig /flushdns to quickly refresh DNS cache.