Solução de problemas de conexão Wi-Fi do Ubuntu 14.04 (outros dispositivos funcionam bem)

Question

Estou com problemas para me conectar a um Wi-Fi que uso com frequência:

• Outros dispositivos, como meu smartphone, se conectam bem a essa rede, e outros clientes não têm problemas para usá-lo
• posso me conectar a outras pessoas por wifi

Então eu acredito que é algo específico sobre essa configuração de wifi que meu Ubuntu 14.04 não está manipulando corretamente.

Esta é a sequência do syslog

wpa_supplicant[1306]: wlan0: CTRL-EVENT-SCAN-STARTED
NetworkManager[940]: <info> (wlan0): supplicant interface state: disconnected -> scanning
NetworkManager[940]: <warn> Activation (wlan0/wireless): association took too long.
NetworkManager[940]: <info> (wlan0): device state change: config -> need-auth (reason 'none') [50 60 0]
NetworkManager[940]: <warn> Activation (wlan0/wireless): asking for new secrets
NetworkManager[940]: <warn> Couldn't disconnect supplicant interface: This interface is not connected.
dbus[769]: [system] Activating service name='org.freedesktop.hostname1' (using servicehelper)
dbus[769]: [system] Successfully activated service 'org.freedesktop.hostname1'
kernel: [ 3578.008660] systemd-hostnamed[6014]: Warning: nss-myhostname is not installed. Changing the local hostname might make it unresolveable. Please install nss-myhostname!
NetworkManager[940]: <warn> Couldn't disconnect supplicant interface: This interface is not connected.
NetworkManager[940]: <info> (wlan0): supplicant interface state: scanning -> inactive
NetworkManager[940]: <warn> No agents were available for this request.
NetworkManager[940]: <info> (wlan0): device state change: need-auth -> failed (reason 'no-secrets') [60 120 7]
NetworkManager[940]: <info> NetworkManager state is now DISCONNECTED
NetworkManager[940]: <info> Marking connection 'Fast & Funny Cafe y Comidas 2' invalid.
NetworkManager[940]: <warn> Activation (wlan0) failed for connection 'Fast & Funny Cafe y Comidas 2'
NetworkManager[940]: <info> (wlan0): device state change: failed -> disconnected (reason 'none') [120 30 0]
NetworkManager[940]: <info> (wlan0): deactivating device (reason 'none') [0]
kernel: [ 3588.723005] ideapad_laptop: Unknown event: 1

Eu tentei:

• desativando o IPv6
• não há system-ca-cert = true nas minhas configurações de conexões para esta rede para excluir, pois outros recursos sugerem

Alguma ideia de como resolver o problema?