Distance from WiFi access point: The farther a device is from your modem/router or nearest WiFi pod, and the more obstacles (walls, floors, etc.) between them, the slower the actual speed will be. You get the best signal (and speed) when you are closer to your gateway or WiFi pod.
Other WiFi networks: WiFi networks overlapping or working in close proximity can cause signal interference and performance issues.
Other websites and networks you visit: Even though you purchased a specific internet speed through Quantum Fiber, the websites you visit may not deliver their services at that same speed. As you stream and surf the internet, the speed of each individual platform may be impacted by their server capacity. During peak hours especially, demand can overwhelm content providers' capacity, causing slower performance and lags when accessing that content or app.