Problems with Wi-Fi on the laptop?

I have a Lenovo laptop that I like to play some games on. I installed Steam, but I noticed that there have been problems with the Internet for a few days, downloads suddenly take a mega long time. I have tried a lot to solve this but without success. The solution methods have always been for steam and I wanted to ask if this could also be due to the laptop, because if I go to the same place with another laptop, everything is OK. Proposed solutions would be very nice.

How does it look if you are connected to the router via a cable? If it is still slow, you can think about the internet connection.

If it is then normally fast, let's take a look at the WLAN ;-)