Recently, I found that none of my bookmarked github.io pages were accessible. At first, I thought they had been blocked, but I later discovered that the issue could be resolved by changing the network settings.
Without further ado, here is the solution:
Solution
1. Open Control Panel\Network and Internet\Network and Sharing Center
2. Click “Properties”
3. Double-click IPv4
4. Enter the DNS Server
First, select Use the following DNS server addresses.
Then enter 223.5.5.5.5.