Your WRT610N is a dual band router. That means it runs 2.4Ghz and 5.8Ghz. If N runs on it's own channel @ 5.8 Ghz, connection speeds can reach 270Mb. That being said, it's conceivable the router is defaulting the N channel to the 5.8Ghz band. I'd go into the router and set the N channel to run on 2.4Ghz.