Speeds Fluctuating

Current download speed via Google is 3.84mps on laptop. Did get a 39.5mps on my iPhone. Not very close to the 1gig that my modem says it is doing. I haven't seen a speed greater than 430mps in the past several weeks. It seems to just go back and forth from about 330mps to 3mps throughout the day. It is getting really frustrating. A Gateway reset solves the problem for maybe an hour.