Wireless Repeater

Hi i live in a 2 story house and i want to get repeater seutp so that i can have wireless access way in our up stairs the problem im facing is that i cant get my two wireless routers to talk to each other… i have a comtrend router ct-5361t and a netgear wndr3400 dual band router. The Comtrend router allows me two options as far as i know an access point and a wireless bridge both i can add a mac address to and my netgear router allows me to have it as a base and or connect to a base but when i configure it and get it setup it will be good for a few minutes and the computers will jump the the 2nd router and act like i dont have internet on the one how can i fix that?