@Mark.B 

If activity speed is shown in MB/s, then it it becomes close to 80Mbps. You will need to multiply it by 8 to arrive at mega bits per second. Over the air rate of 866Mbps will generally not allow more than 60% of this as actual Ethernet throughout delivered on a capable 5GHz AC 2x2 client. I have Aruba Instant 215 AP and I get 580Mbps throughput if I am the only one using and am 12 feet away from the AP in almost clear LOS. On wired port, I get close to 900Mbps.

You may want to test with a newer cell phone or a laptop also.

Hi @Mark.B,

I cannot speak to the Firestick, but it is possible that one device just cannot go any faster.

1) what speed is your broadband?

2) what wifi speeds do you get on your phone/tablet/laptop?

3) have you disabled Band Steering and Air time fairnes (and MESH if your not using it) and connected the device(s) to to the 5.8GHz radio only?

With my iPhone XSM and FIOS Gigabit, I get anywhere from 300-500 Mbit/s DL & UL on both the EAP225 and EAP245.  The 245 is slightly / generally faster under load (20+ clients).  But, often times the speeds will vary depending on which speed test program I use (Ookla, SpeedSmart, Fast.com, DSL Reports, etc,)

If you want to just test Wifi performance (sans internet) you'll need to use iPerf or similar.  For which you will need a "server" PC connected via Ethernet and a client wireless PC and run the iPerf App on each.

-Jonathan