Unable to establish WiFi connection on Raspberry Pi. What to do?

Question

linux

Ralink RT2571MF WiFi adapter ( photo ) connected to Raspberry Pi 1 B. Minibian OS .
In minibian I work as root.
Followed the instructions :

$ apt-get update
$ apt-get install firmware-ralink wpasupplicant iw crda wireless-regdb wireless-tools -y

$ nano /etc/network/interfaces :

auto lo
iface lo inet loopback

allow-hotplug eth0
iface eth0 inet dhcp

allow-hotplug wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

$ nano /etc/wpa_supplicant/wpa_supplicant.conf :

network={
    ssid="SQT-0091"
    psk="password"
}

$ reboot
...

$ iwconfig wlan0
wlan0     IEEE 802.11abg  ESSID:"SQT-0091"
          Mode:Managed  Frequency:2.437 GHz  Access Point: 20:54:76:F4:31:B7
          Bit Rate=54 Mb/s   Tx-Power=20 dBm
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:on
          Link Quality=26/70  Signal level=-84 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:2   Missed beacon:0

After a few seconds

$ iwconfig wlan0
wlan0     IEEE 802.11abg  ESSID:off/any
          Mode:Managed  Access Point: Not-Associated   Tx-Power=20 dBm
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:on

See the dmesg output in the comments.
Solution attempts that didn't fix anything:

$ touch /etc/modprobe.d/b43.conf
$ echo "options b43 pio=1 qos=0" | tee -a /etc/modprobe.d/b43.conf
$ reboot

From here.

$ touch /etc/modprobe.d/b43.conf
$ echo "options b43 pio=1 qos=1" | tee -a /etc/modprobe.d/b43.conf
$ reboot

From here.

$ wget http://www.elektronenblitz63.de/download/wicd-1.6.x_addon01441.tar.gz
$ apt-get install --reinstall wicd
$ tar xvf wicd-1.6.x_addon01441.tar.gz
$ cd wicd-1.6.x_addon01441
$ ./install_wicd_addon
$ service network-manager stop
$ killall wpa_supplicant
$ service wicd restart

From here.
$ nano /etc/modprobe.d/mac80211.conf :
options mac80211 probe_wait_ms=1000
From here.

Answer 1

If you're trying in an office or close to office buildings, make sure you don't receive deauth packets. Now popular technology is increasingly common. The bottom line is that when an alien wifi network is detected, a deauth packet is sent to all its clients and the connection is broken.