Hi, I have trouble with my 13-yr old son getting on DOTA in the middle of the night.  Can I block access to some websites on the  ATT Uverse router? 

Setting Up Your Own Router The Arris BGW210-700 BGW320 is an advanced residential gateway that supports VoIP, IPv6, video delivery, security firewal

We have the AT&T U-verse router 5031NV-030.  Sadly, this router doesn't contain features most routers have for over a decade to restrict access times