bandwidth is a scam. lossy intermittent connectivity wont be improved by bein able to download movies real fast with short unnoticed disconnections.
its like drinking the water in flint. they can increase the water pressure, but its still awful drinking water through corroded, poisoned pipes not fit for handling the liquid traffic.
this is assuming you dont have hardware failure of some type in your home networking setup, or damaged cabling at some point indoors/outdoors. realistically the best first step is to just get a tech out there to do all they can (or more likely, are willing to) attenuation, outside/box/drop cable replacement, etc
once you are 100% certain its not on your end beyond that are nuclear options that involve DOCSIS testing your neighborhood, outside agencies and getting your neighbors involved for a node split/street dug up basically, but thats a little beyond the scope of this explanation.