I have had a Lenovo IdeaPad Flex 5 for five months and have a weak internet connection on my laptop all the time. By a weak internet connection, I mean that websites sometimes take a few minutes to load. I have a good internet connection on my computer, cell phone and other devices, but not on my laptop. It can't be because of the distance to the router, because when I sit next to the router, I still have a bad internet connection. I would be happy if someone has a solution for the problem!
You could try out maln driver update of the network card. Otherwise just try Lankabel.
Cable will probably be heavy. But a driver update is certainly not wrong ^^
You can do driver updates through Lenovo Vantage. Is either pre-installed or you can get it from the Windows Store.
As suggested, a driver update (if possible) is not wrong. You could also see if you can go to 5GHz. The 2.4GHz band is mostly paved all around (with me currently 29 networks all around but only 1 5GHZ.
Some Lenovo laptops no longer have a network jack, but since there are very powerful USB network cards, this should be solved quickly.
I would reset all network settings and restart Windows, maybe your Lenovo will connect better to the Wi-Fi. What do you see in Start → Settings → Network and Security → WLAN → Properties → Connection Speed?