Do you mean the WiFi feature on the phone actually toggles itself off, or it just loses connection with the router?  And you have a connection (can browse on the phone), but then it stops?  Do other devices connected to WiFi have any issues staying connected?

Simply rebooting the router will often clear up WiFi problems, do so if you haven't tried already.  If you have password security enabled on router, try a different type.  For instance if you are using WEP, try switching to WPA or WPA2.  WPA and WAP2 are more secure than WEP, so WEP should be avoided.

The fact the router is not AT&T should have nothing to do with it.  The problem is more often with the router, rather than the phone.  And the fact that you just replaced the router somewhat reinforces this theory.  What brand and model router?

the wifi on my phone toggles itself off. also, everytime it happens i have to establish a new connection to my router(put in router password). My phone is the only phone this is happening to. The settings on the modem/router are set for wpa2

Do you happen to have the AT&T Hotspots app active on your phone?  I have heard that this app was causing problems for some people as they tried to stay connected to Wi-Fi.

I just rebooted the router and so far my wifi connection on my phone hasn't turned off. I just hope this continues to be the case. Thank you for the suggestion.