Recently my Raspberry Pi 3's wireless link got slow. My ISP was the first suspect, but it turns out the Pi3, and only the Pi3, exhibits slow ping (5ms) and low throughput (2 Mbps). Formerly, ping was about 1 ms and throughput about 20 Mbps. The change was sudden, in the space of an afternoon. There was some recovery overnight, but not enough to use things like YouTube, which formerly worked well enough to be useful.
One reasonable guess is that a new neighbor has fired up a WAP that's interfering with the Pi's wifi connection. Are there any software tools that run on Raspberry Pi3 or a 10.7.5 iMac which can help to detect wireless conflicts?
My WAP is an Apple Airport Extreme of great antiquity. It has "just worked" since setup and I've never looked closely at it. It is locked, and uses WPA encryption.
Thanks for reading!
bob prohaska