Filtered? Is that the same as censored?

Yes
 

Yes ...

http://en.wikipedia.org/wiki/Interne...ip_in_Thailand

small excerpt...

Censorship of the Internet in Thailand is currently for website access only. Unlike China's “Great Firewall”, which censors all Internet traffic including chat conversation via Instant Messaging, Thai Internet users are still able to interact with other users without being censored. However, current policy is to use a system of transparent proxies so that the user receives system, server, TCP and browser error messages when trying to access blocked sites leading the user to believe that the failure is caused in the Internet itself.

http://en.wikipedia.org/wiki/Interne...ublic_of_China

Included a wiki for China to because it includes many other methodology which I thought was interesting.

Is it a TOT router? If it is, the username is admin and the password is tot.
If that doesn't work, you can hit the reset button and reconfigure the router. after you reset it, it will ask for an authentication login to authenticate into the TOT network, usually the username to login to the Internet (not login to the router) is yourphonenumber@tothome, and the password is yourphonenumber, but you should check with the service provider, or if you're in a rental house, check with your landlord.

Someone hacked my router once while I was in Thailand. I just reset the router and used homephone@tothome to login again.

No, it's a True-supplied POS.