iwlwifi
i recently noticed that my wifi was really slow. checking it revealed that i only had 1Mbit as bitrate, while the link quality was fine.
after fiddling around with various settings on the ap the reason turned out to be a b0rken iwlwifi driver. disabling bluetooth in the bios together with this module configuration helped:
# /etc/modprobe.d/iwlwifi.conf
options iwlwifi bt_coex_active=0 swcrypto=1 11n_disable=8
cf. debian wiki
behold:
$ iwconfig wlan0
wlan0 IEEE 802.11abgn ESSID:"???"
Mode:Managed Frequency:5.22 GHz Access Point: ???
Bit Rate=135 Mb/s Tx-Power=15 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Power Management:on
Link Quality=54/70 Signal level=-56 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:12 Missed beacon:0