Broadband cable extension

Hi. This is my first post on here so hello everyone and hope you're all doing well.

My broadband hub is too close to my TV and soundbar etc and it's causing interference with the Internet and secondly I'd like to put the hub more central in the house to allow for better coverage especially in the back of the house where we have multiple smart devices, speakers, washing machine etc.. the question is where can I purchase a cable long enough to reposition the hub without losing quality. I'd say 3m extension would do the trick. Thank you. Paul.