If your internet connection is slow or not performing as well as you want, you can take several actions.
Reposition your modem. Modem/router signals are strongest the closer you are without any interference. Being further across the room from your modem or having walls between you can result in a weaker signal and slow speeds. Putting your modem up high rather than on the floor should help too. If moving closer to your modem or moving it closer to you doesn't help then consider investing in a better router, a Wi-Fi extender or wire in with an ethernet cable.
Reduce network congestion. Having too many people online at one time can cause a "traffic jam". This is more prominent at lower speed tiers. If you have an important work meeting asking another household member to pause their Netflix for an hour could help. If your household isn't the problem it might be a provider problem. Compare and switch to an internet service with better typical evening speeds. You can also hop off your broadband connection and swap over to your mobile's personal hotspot if your plan allows it.
Replace or upgrade your equipment. When nothing else works, it might be your equipment itself. Compare to find a new router – just make sure it's supported by your provider.
You can also try running a virus scan, updating your network drivers or closing background applications.