wireless networking – Why is my AC Wi-Fi speed about 150 Mbps but Windows claims it is 325 Mbps?

I have a Lenovo Ideapad l340 with a built in Realtek 8821CE Wireless 802.11 AC network adapter. The fastest download speed I can reach is around 150 Mbps, even though Windows claims the double:

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My machine is close to the router and other devices with the same router are much quicker. What can be the problem?