I wonder who decided it might be a good idea to put Bluetooth and WiFi on the same 2.4 gigahertz spectrum?
It was relatively easy to enable Bluetooth and connect my wireless headphones in Arch Linux. I noticed however that afterwards my internet connection would inexplicably slow to a crawl whenever I connected. Disconnect, and it would be fine again. Connect, and again, virtually nothing — especially if sound was playing through the headset.
The easy solution was to connect my WiFi on the 5 Ghz band. Done. It worked. No interference. And that could have been that. But it was still bugging me. I still wanted to know why. I still wanted to fix it.
(2.4 Ghz gets better range than 5 Ghz because it's a lower frequency so sometimes it actually gives me a more stable connection from further away.)
I found a few possible solutions. I tried changing the WiFi channel on my router, and that helped a little bit, but not quite enough.
In the Arch Wiki they have a small section about Intel combined WiFi and Bluetooth cards and playing with the coexistence setting and I thought I was onto something.
They suggested adding the following to /etc/modprobe.d/iwlwifi.conf:
options iwlwifi bt_coex_active=0
But nope. Nothing. No difference.
After some searching, a post in the Arch Forums put me on the right track.
In the end, adding this to /etc/modprobe.d/iwlwifi.conf fixed it for me:
options iwlmvm power_scheme=1
Reboot and you're all good.
Seems to be the same fix as described here, but for a different symptom.
Anyway, hope this helps someone else. Happy hacking!
ps.
- Jim Mussared put me on to this page about iwlwifi and platform noise which gives a bit more information about why this works.