So I bought an outdated C9 AC1900 for $15 to upgrade my Airport Express. Turns out it's probably not much faster :( I think I was enamored by it's appearance.

My connection is cable 500mbps / Spectrum.

Physical environment is a small apartment with many networks. I only stream content at 720 through Google TV and plan to plug that into the extender with an adaptor for Google TV. 

I'm going to speed test everything out if interest.

Initially I'm in need of a range extender 5ghz/2.4ghz that won't slow down the connection at all because of it's capabilities.

Any recommendations?

If I do turn around and sell the AC1900 because it's might not be any faster than my Airport extreme any recommendations?

I hear that newer versions are more resilient to "noise". 

The RT-AC66U is one option I'm aware of but I heard of an auto-negotiation issue with cable choking speeds.

Thank you