

tried auto and manual 2.4Ghz and 5Ghz channels selection (by scanning the other networks around).My AirPort Extreme is on firmware 7.6.4, set up as follows: I've also changed all UTP cables to be CAT.5e, in order to support gigabit speeds. Youre right that your A1408 (2010 3 spatial stream 802.11n) AirPort Extreme runs NetBSD, but Apple has never exposed a way to SSH or telnet in, nor have they exposed a serial console to do the same thing locally. I tested the connection by directly sticking the cable into the MBP (via the thunderbolt ethernet adapter) and got 850 / 200 Mbps, so the connection from my provider does work as expected.
SPEED OF APPLE AIRPORT EXTREME A1408 HOW TO
Since the low speeds are consistent over wired / WiFi (I was expecting the Mac Mini to outperform the others, since its on gigabit ethernet), this will not be a discussion about how to select the best channel (tried auto or manual setup, with it on different channels) or change its placement (this is consistent even with the MBP right next to the router) to get better reception. The low speeds happen both on WiFi and wired (I have an iMac, a MBP, an iPhone 6s and an iPad Mini that connect via WiFi, on the 5Ghz network and a Mac Mini that is wired into the router), with my wireless devices getting full strength signal and connecting at 450 Mbps.

The best I ever got were around 180 / 200 Mbps, but that only happened once. My plan is 1000 / 200 Mb (down / up - Romanian RCS & RDS, Fib), however, I'm getting averages of 90 / 80 Mb speeds on. I have an AirPort Extreme A1408 (5th Gen), that is connected to the internet via a UTP cable (wall plug, the internet provider has its routers in the basement of the apartment building).
