I have the Archer D50. In the user guide (page 52) there's written:

9.    Click Add a New Keyword. You can add up to 200 keywords
for both Blacklist and Whitelist. Below are some sample
entries to allow access.
1 ) Enter a web address (e.g. www.tp-link.com) or a web
address keyword (e.g. wikipedia) to only allow or block
access to the websites containing that keyword.
2 ) Specify the domain suffix (e.g. edu or .org) to allow access
only to the websites with that suffix.
3 ) If you wish to block all Internet browsing access, do not
add any keyword to the Whitelist.
10.    Enter the keywords or websites you want to add and click
Save.

I go to the parental, but when insert, for example .info in the box (for to blocking all the websites with the extension ".info"), i have the foolowing message:

"Please input correct URL".

I don't understand why.