Enabled bluetooth affects wifi download speed

I use librem 15v3 with openSUSE Tumbleweed.

I just noticed that if I enable bluetooth and use it to play music, then my wifi download speed is greatly affected. To be sure I ran speedtest few times with bluetooth enabled and disabled. The results are consistent:

  • with bluetooth disabled download speed is around 6Mbps
  • with bluetooth enabled download speed is around 0.2Mbps

Surprisingly, upload speed stays around 1Mbps regardless of bluetooth.

I have kernel 4.19.8 and set options ath9k btcoex_enable=1