Why is my Wi-Fi so slow on MacBook Air M2 compared to wired connection?

I have a Gigabit internet connection. When I connect my MBA using a 3 foot ethernet cable to the router I get 800+Mb connection speed. When I unplug the cable to use wifi to the router (so I'm 3 feet away) I get 40Mb speeds. When I go elsewhere in my house and use the mesh network and plug an ethernet cable from the mesh unit to my MBA I get 160Mb. Unplug the cable and it's 35Mb.

I have

• power cycled the router and the modem
• tried two different wifi channels
• rebooted the MBA
• I'm running MacOS 15.4.1 (24E263)

I've searched around the net but haven't found anyone previous threads that have the same problem. The 40Mb speeds aren't terrible but the I do notice them when downloading content from the net.

Any obvious things I should try that I haven't done? I haven't changed any network settings.

Thanks!

[Re-Titled by Moderator]