Question
What is the current proper way to force reconnection to a WiFi access point? (Or even better: automatically reconnect after the connection is dropped?) The only way to reconnect that has worked so far is to re-plug the USB WiFi dongle or do a full reboot.
Problem
Every so often (2-5 times/day) when the WiFi connection drops, the Pi never automatically reconnects to the WiFi network. I would like to run some command(s) to reconnect to the WiFi network, since it doesn't seem to do so automatically with a USB WiFi dongle, whereas it consistently auto-reconnects with the onboard WiFi when testing over a shorter distance. This suggests something might need to be reconfigured (or worked around) for the WiFi dongle to auto-reconnect.
(Note: The access point is both somewhat far away from the Pi and not the most reliable. Unfortunately, neither can be moved closer to the other, and the onboard WiFi doesn't "reach".)
(EDIT: Clarity)
Specifications
Raspberry Pi 3 Model B v1.2 running Raspbian Stretch Lite with latest updates and kernel version 4.14.98-v7+ as of Mar 3 2019. (EDIT: Updated from 4.14.79-v7+ to newest stable packages & kernel. This helped make the connection more reliable, but once it drops it still stays dropped until reboot.)
USB WiFi dongle plugged directly into Pi: "5dBi Long Range WiFi for Raspberry Pi" (https://www.amazon.com/gp/product/B00YI0AIRS) with a Realtek 8192CU chipset.
$ lsusb
Bus 001 Device 005: ID 0bda:8178 Realtek Semiconductor Corp. RTL8192CU 802.11n WLAN Adapter
Configuration
Default DHCP setup, no static IP, /etc/network/interfaces left untouched.
/etc/wpa_supplicant/wpa_supplicant.conf:
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=US
network={
ssid="MySSID"
psk="MyPassword"
}
Onboard WiFi disabled by adding the following line to the end of /boot/config.txt:
dtoverlay=pi3-disable-wifi
/etc/modprobe.d/8192cu.conf:
# Disable power saving and USB selective suspend
options 8192cu rtw_power_mgnt=0 rtw_enusbss=0
Likely defaults, but nearby files are as follows:
/etc/modprobe.d/blacklist-rtl8192cu.conf: blacklist rtl8192cu
/etc/modprobe.d/blacklist-rtl8xxxu.conf: blacklist rtl8xxxu
$ iwconfig wlan0
wlan0 IEEE 802.11bgn ESSID:"MySSID" Nickname:"<WIFI@REALTEK>"
Mode:Managed Frequency:2.437 GHz Access Point: 01:23:45:67:89:AB
Bit Rate:144.4 Mb/s Sensitivity:0/0
Retry:off RTS thr:off Fragment thr:off
Power Management:off
Link Quality=100/100 Signal level=60/100 Noise level=0/100
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
$ ifconfig wlan0
wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.123 netmask 255.255.255.0 broadcast 192.168.1.255
[...]
I chose this WiFi chipset after reading from multiple sources that it was especially plug and play with the Raspberry Pi. It is, to a point... However, when trying all of the various methods detailed below to restart WiFi without rebooting, I either get an error, nothing happens, or the WiFi goes down and won't come back up without a reboot. Until now, the only reliable way I have found to remotely reconnect is to periodically reboot the Pi; an ugly solution for sure.
What I've Tried (without success)
ifconfig interface down/up:
sudo ifconfig wlan0 down sudo ifconfig wlan0 upBrings the interface down and up, but it never gets an IP address.
wpa_cli stuff:
wpa_cli -i wlan0 disconnect wpa_cli -i wlan0 reassociateor just:
wpa_cli -i wlan0 reassociateBoth result in the WiFi never reconnecting/no IP address.
In wpa_cli interactive mode, I get an "Association request to the driver failed" error:
$ wpa_cli -i wlan0 wpa_cli v2.4 Interactive mode > reassociate OK <3>CTRL-EVENT-SCAN-STARTED <3>CTRL-EVENT-SCAN-RESULTS <3>Trying to associate with 01:23:45:67:89:ab (SSID='MySSID' freq=2462 MHz) <3>Association request to the driver failed <3>CTRL-EVENT-SCAN-STARTED <3>CTRL-EVENT-SCAN-RESULTS <3>WPS-AP-AVAILABLE <3>Trying to associate with 01:23:45:67:89:ab (SSID='MySSID' freq=2462 MHz) <3>Association request to the driver failed ...(This just loops until I quit with
q.)Running wpa_supplicant directly:
sudo killall wpa_supplicant sudo wpa_supplicant -B -c/etc/wpa_supplicant/wpa_supplicant.conf -iwlan0 -Dnl80211,wext- Another combo:
followed bysudo killall wpa_supplicant sudo dhclient -v -r wlan0sudo systemctl restart dhcpcd.service sudo dhclient -v wlan0 - Manually deleting the lease file before running some/all of commands in the above two bullets:
sudo rm /var/lib/dhcpcd5/dhcpcd-wlan0-MySSID.lease - All of the above combined with re-enabling the onboard WiFi in
/boot/config.txt, but this doesn't seem to be part of the problem.
