This is a common complaint when the Internet Service Provider's link to the Internet is full or max'd out.
There is usually nothing ever wrong on your gear.
That said, please read my PSA (public service announcement at https://www.cnet.com/forums/discussions/this-just-in-reboot-your-internet-modems-and-routers/ as this can result in your complaint so may as well get that out of the way.
I have 40mpbs speed internet. I can buffer 1080p 60 fps easily. But in the afternoon (1.30pm to 5pm) everyday, all live streams keep buffering (twitch and facebook live streams) for all video qualities over 480p. youtube works fine. Please help.