Ubuntu 17.04 and 17.10 have an issue on some computers that can’t handle MAC address randomization while Wifi scanning. Wifi MAC randomization is a good thing, but not totally debugged yet on Ubuntu.
Workarounds to fix Ubuntu 17.04/17.10 Wifi dropouts
The telltale sign of this problem is seen by
as messages like
mwifiex_pcie 0000:01:00.0: wlan0: already connected ieee80211 phy0: mwifiex_cfg80211_sched_scan_start : Invalid Sched_scan parameters
I tried each of the workarounds below. Sometimes, Wifi still drops. In those cases, I Bluetooth tether to my phone (phone on Wifi), which seems completely stable.
Disable NetworkManager MAC randomization
Note: Ubuntu 17.10 may have this already set.
- add to
- restart NetworkManager
sudo service network-manager restart
Disable Wifi power management
wifi.powersave = 2
Wifi module reset
The above techniques work for SOME but NOT ALL Microsoft Surface Pro 3 for Wifi on Ubuntu 17.04/17.10. A stronger method that does work with periodic resets is to remove/reinsert the Wifi kernel module and restart Network Manager.
- create a script
#!/bin/sh modprobe -r mwifiex_pcie modprobe mwifiex_pcie service network-manager restart
- make the script executable
chmod +x ~/wifi_reset.sh
- Every time your Wifi disconnects due to the
dmesg -wmessages noted above, use
When all else fails, I Bluetooth tether to my Wifi-connected smartphone. Yes this is limited to 1.6 Mbps upload/download. It’s just a backup method.
Please see the comments below for other methods that have helped e.g. for
iwlwifi Intel WiFi adapters.