I was browsing recently and suddenly when I tried to visit facebook my browser showed me an error message telling me that this domain is blocked due to content filtering, If you think this shouldn't be blocked, please
contact your network administrator.
I noticed that I was unable to visit any site that uses SSL encryption such as facebook, google, twitter etc but can visit any site that doesn't have an SSL encryption and I thought it was a virus on my computer but I was wrong.
I even tried changing my browser settings from using system settings to automatically detect connections but still, the error still persists.
What I did to fix this domain is blocked due to content filtering error
I tried finding out the cause of the problem by using Ultrasurf software to connect my computer to see if it works and it did work, that was when I knew it was a network problem and not a virus.
I deactivated the Ultrasurf and disconnected my phone data connection which I used to send the connection to my computer since the problem is because the connection in which my phone is connected was not trusted so i had to disconnect and connect again to fix such error and it worked.
Whenever you see such error it's possible that your phone or modem is connected to the wrong proxy Ip address or not trusted and the solution is to disconnect your network and connect it again which allows your phone or modem to connect to the right and well recognized network.