I have 3 DIR-655 routers in the house and 1 DIR-601. 2 Touchpads in the house and have had no problem using them. Using WPA2 on the routers. Although my TP does drop occasionally when using wifi tether on my android.
None of mine can maintain a steady connection. Sometimes I'll get lucky but usually when I leave it overnight it'll crap out by morning.
Would you mind sharing what wireless settings you are using?
Thanks