Using IP and port filtering at the router to block a domain?

Yes: whoever said you could do it that way is very wrong. 

Hi BBIssues 

Welcome back to our Community Forums and thanks for your post. 

If you want to block specific websites navigate to WebSafe via your Virgin Media login and you can block categories of websites as well as specify individual ones to block. 

For more info see here

Websites can be blocked via WebSafe, but not in a timed way. Also it only blocks Virgin DNS, so if the DNS server is changed by the user, the site is no longer blocked. You can stop specific devices accessing the internet during a time range, but that is all.