How to speed up wifi repeater?

I’ve setup an Asus RT-N12 router as a wifi repeater. But It’s about 30% slower than wired speeds or other wifi speed.

 Internet  -----Primary WifiRouter------N12 Router (repeater)---- Win 10 Desktop
                               |------Win 10 Laptop

Measurements

• Windows 10 Laptop download speed: 110Mbps
• Windows 10 Desktop wired download speed 110 Mbps
• Windows 10 Desktop wireless via N12 Router: 80 Mbps

I read somewhere that the Repeater router may be using the same channel for both ends of it’s repeated link (upstream and downstream)

Is there any way to speed this up and get close to the source Internet speedH/