Major Lag Spikes While Playing

Hey so, I have some heavy lag spikes when playing. But any other server or literally anything else I do with the internet has no issues. Is there something I can do to fix that? This is both on a vanilla client and using the Wynncraft Plus modpack from curseforge.

It's not even fps drops, pretty sure it's my connection. because I will be walking around fine, hitting stuff. and then usually I can tell that I am de-syncing because the music stops or starts to stutter. before eventually all playing at once as I catch back up.

Video for reference of what it is like. It happens right at the start and close to the end of the video. There will be times it is constantly as it is near the end of the video, with no breaks of a stable playing experience.