TL,DR: If you play games or do voice/video chat, then the latency figure is what you need to pay attention to instead of the bandwidth figure. If the connection to your router is consistently good, yet your internet seems slow at unpredictable times, then you might have the symptom so-called bufferbloat. You will need to setup a thing called Smart-Queue-Management on your router. You will have to install a third-party open source software called LEDE, because no router on the mass market right now has it installed by default.