I am currently puzzled, i tried to configure a second wifi router in my home but it does not get the maximum speed same as out first wifi router. the original wifi router when i am connected it gives me around 500Mbps but the second router only gives maximum of 80Mbps. the second router is a Xiaomi Mi Router 4A.
When you set up range extenders over wifi, I believe it uses half-duplex. If you connect both routers with an ethernet cable you will get a faster speed over the 2nd wifi.
I use to have an array of routers connected over wifi, until I couldn’t take the pain any longer and fitted ethernet cable. You are wasting your time trying to improve your situation with what you’ve got.