My internet is laggy

Hello,
ok so heres my problem i am sharing a wireless internet with my partner in the house and his connection is just fine wiel my connection is way lagging i get ping rates up to 1000 pps and this happens every time he starts using it (thats my suspicion) because if i change the wpa key the internet runs smoothly. btw im connected directly to the router i dont know what he runs wiel his on the internet but he makes my internet lagging so much