Internet latency

99% of the time I will have a fluctuation of both upload latency/bufferbloat around 500-7,000, and a download latency of 80-320 with lower speeds following suit, going from 1100 download 40 upload to 600 download 22 upload. I use a CAT 6 ethernet cable from the router to my pc, this doesn't happen on just this device. I've upgraded plans, gotten a new router from Xfinity, minimized the devices connected to the router at a time, messed with router and computer settings. (yes I've unplugged the router/reset it plenty of times) It makes things basically unusable taking way to long to load, cutting out entirely, buffering etc... surfing the web, playing a video game, watching youtube or a movie. I've done everything I can on my end I feel like n this has been going on for a little over a year. What can I possibly do? Please help