LG Optimus Extreme Wifi "authentication error"

My LG Optimus Extreme for Straight Talk is connecting to mobile data just fine, and it picks up my wifi signal, fine. The connection was working well for a few days, but then suddenly it disconnects from the wifi, and for several days it has been having the same issue. It picks up the wifi signal, which will be a strong signal. But when I go to connect, it says "authenticating," and shows a weak signal and will not connect. Any way to fix this...?