Assuming you mean an EA6900? What firmware is it running on and what hardware version is it? hardware can be found on the label on the bottom. if it just says 6900 then it is a 1.0 hardware if it says 1.1 then that is the hardware.
edit: I forgot that they indeed had a EA6700. Still could be a firmware issue like in the EA6900. Did it recently update? is there an newer or older version on the Linksys website to try? The EA6900 has an issue with the latest version of firmware that is similar to what you described. Randomly disconnects users.