Airport Express is cutting a 60mbps connection down to under 20mbps

Can you give us a layout of your general network?

 

How the Express is connected to the Extreme, the Internet speed, what is connected to the Express and how.

 

The Express has limited speeds over WiFi when compared to the Extreme. You may be maxing out its wireless speeds.

 

If its still within the 14 days grace period you can take it back and exchange it for an Airport Extreme.

 

Your best bet would be to run an Ethernet drop from the Extreme to the Express. Even then you are limited to 100 Mbps based off the 100 Mbps WAN port.

 

You're running the express as a repeater. It reads in the data, then spits it back out then reads it back it in. That alone will cut your total bandwidth. Giving both and Ethernet port will cut traffic and interference and boost throughput.

 

Well... I would begin by looking at the transmit rate between the Express and the Extreme. This is verifiable in the AirPort Utility. Divide that in half because you are having it run as a repeater and take off a bit for overhead and you have the highest speed you will see. You can try a factory reset, but it is likely that it just has a slow transmit rate and as a result shows the speed decrease you see. Wiring it in via Ethernet would eliminate this problem and still work as an AP rather than repeater.