I just bought a MR3420 router and connected it to my 100 Mbps ethernet WAN, but the wifi speed is less than 50 Mbps even when I put my PC right next to the router.

This is disappointing as the router claims to support 300Mbps.

I tried with a different router and got the expected 100Mbps wifi signal so its definitely not a WAN/ethernet issue.

Is there a way I can improve the speed of the MR3420? I dont want to have to return it to the shop.