Comment 19 for bug 1719210

I have to correct my earlier statement (comment 14), the linux-firmware package update didn't fix the problem after all - it seemed to work for a while, but I was mistaken. Now, however, I've gotten it working. The correct fix is to add the following line to the end of /etc/modprobe.d/iwlwifi.conf

options iwlwifi bt_coex_active=0

After a reboot, you can test if the option is enabled with

cat /sys/module/iwlwifi/parameters/bt_coex_active

(Should return 'N').

Since I added that option, I haven't had any further issues with my Sony Bluetooth Speaker (or WiFi).