Internet speed?

I'm having a problem with my internet. You should know that there are five people in the house. We would normally have purchased a 300 Mbps connection, but everywhere we go we get a connection of around 100-200 Mbps. But in my room it sometimes drops below 1 Mbps, then back to 70 Mbps, then 10 Mbps. So it's completely inconsistent, and when I'm gaming, even if I get 50 or 70 Mbps, it lags completely, so I can't play. What could be the problem, and is there a solution that might work?