Ping unstable

I upgraded my internet speed so i received a new modem which the technician install now I have better download but the ping is not stable used to be more stable with old speed and old modem model Im a streamer i can't play any video games in a proper way literally unplayable please help or i have to change the company nothing personal but the ping is one of the most important thing when it comes to video games, HELP ME please and thank you.