help reducing ping

My house only receives 15mbps and I get crazy lag spikes. Ill be steady at around 80-100 ping then all the sudden I jump up to 800-1000 for a few seconds then back down to 80-100. Anyone know how to fix this? I've tried shutting off background apps and my wifi is wired. I've heard of ppl using bloxstrap and fastflags to reduce ping but idk if thats bannable or not. any help is appreciated.