Frequent Lags

Hi, I have recently downloaded the WotLK (old) client and created a character in the Icecrown server. Since then I have been frequently experiencing latency lags that lasts from seconds to minutes and it makes the game unplayable at times. My roommate who is connected to the same Wi-Fi as me isn't getting any of the lags that I have been experiencing and I can also play other online games without any lags. I have been searching the internet for ways to resolve this issue but so far I can't find any solutions. Can anyone please tell me how I could resolve this latency issue?