Airport Express only getting 0.5 mbps

[convergent]

I have a strange problem that I'm hoping to get some help here for. I have an in home network of an Airport Extreme and Airport Express, extending the wireless network via a MOCA network. I am pretty sure the MOCA network is working fine because I have a home office... Mac and Dell computers, and a Tivo Roamio Plus serving multiple Tivo Roamio Minis over the same network. No way I'd have multiple HD streams working at this slow rate.

So I downloaded a speediest app to my iPhone 6s Plus and when I run it downstairs while I'm connected to the Airport Extreme, I get pretty 10-20mbps up and down. When I'm upstairs connected to the Airport Express, I'm getting less than 0.5mbps up and down. If I run a speed test from a computer upstairs connected directly to the MOCA network by cat5, I get 60mbps down, 10mbps up, which is closer to what I should be getting.

So why am I getting such slow speeds through the Express? And also why am I get about 1/5 the speed I should get from the Extreme via wifi... although that is plenty for my phone.

Any ideas? I've tried the usual reboot of everything.

 

[convergent]

I just switched the Express from "802.11n (802.11b/g compatible)" to "802.11n (802.11a compatible)" and now I'm getting 30mbps down, 10mbps up, just like the base (Airport Extreme). I'm guessing there is some old wifi device somewhere here in my house that is slowing down the network.

This should solve my problem for now. Still not sure why I'm getting half the downstream via Wifi as I get wired, but this is plenty for a smartphone.