It shouldn't, but apparently it is.

The question was, what if I don't use a router and connect the 8630 directly to the modem.

Hayden, with a physical line bandwidth of 120 Mbit/s, getting a payload throughput of about 40 is realistic and normal. Just like any other shared-media network (e.g. WLAN), actual throughput is...

... and how pathetic is it that TP-Link don't put out an official update that makes their product work properly?

(2) You wouldn't set it up as a repeater, you'd run it as a 2nd access point. Use the same SSID and passphrase as on the main router, set the two up to use different radio channels, and that's it....

I'm so glad I bought them through Amazon. So the original manufacturer doesn't have the current version of the product in stock? That's about as steaming a pile of bullshit as you can possibly...