I am not sure but I am about to find out soon. Right now we use 200 mg speed and and works really well. Next month they are going to drop us to 100 mg speed, but this is a small apartment so I believe it should work pretty good.
I would suggest putting this extender in the middle of the router and the farthest device. Test it out in several “middle” areas so that you can see the signal strength coming from the router to the extender, and the signal strength that the extender is providing to the farthest device.
The Netgear N300 has proven itself as a very dependable and performance proven unit. You will not find a better WiFi extender for the money, I tried many higher priced units and this model has and is serving me well