I have a mid 2015 Macbook Pro.
When at home, WiFi is as good as can be expected, approx 30-40mb down.
I stay away from home at another house during the week and whilst all of my other devices achieve good WiFi (phone, tablet, firestick) my MBP almost grinds to a halt.
Whilst at that location I set up my phone as a hotspot and connected the MBP and that worked as it should, all fine, approx 10mb down. When I then switched back to the in-house WiFi however, it was back to an almost non-existent crawl.
I'm not big on networking issues so not sure where to look for any clues as to what could cause this.
Are there any tests I could run which would allow me to narrow down what the problem is?
EDIT
Ok, really weird behaviour now...
I decided to strip back and not have anything attached to my MBP and run the test again (using speedtest.net). Approx 70mb down. Wtf! Then as I add things back on, one by one, power supply, external monitor (video, not audio), keyboard (usb, music), headphones, usb hub (DAW dongle and external drive) it degrades with each addition, approx 10mb each (including headphones which are passive surely).
Has anyone seen anything like this before?