Since i plugged tv cable to my modem

, when i play games like cs go , timeout happens once every 1 minute for a second or two which causes me to lose 1vs1 situations , until i turn off the tv or remove the cable. 

i really like this modem because its good for games and the ping stays stable when other people connects unlike my old 8968 v4 which had terrible ping spikes . can we fix this problem or atleast know what is causing it to lag every minute .