oot@armadillo:~# nmcli c up gsm-ttyUSB2 
Error: Connection activation failed: No suitable device found for this connection.
root@armadillo:~# tail -F /var/log/syslog
Nov  4 02:19:26 armadillo nm-dispatcher: req:4 'up' [eth0]: start running ordered scripts...
Nov  4 02:19:26 armadillo ntpdate[2503]: name server cannot be used: Temporary failure in name resolution (-3)
Nov  4 02:19:28 armadillo avahi-daemon[641]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::211:cff:fe1d:774b.
Nov  4 02:19:28 armadillo avahi-daemon[641]: New relevant interface eth0.IPv6 for mDNS.
Nov  4 02:19:28 armadillo avahi-daemon[641]: Registering new address record for fe80::211:cff:fe1d:774b on eth0.*.
Nov  4 02:20:57 armadillo NetworkManager[832]: <info>  [1478193657.6063] keyfile: update /etc/NetworkManager/system-connections/ether (e7436e3e-c854-4456-9713-bfc8a608e136,"ether")
Nov  4 02:20:57 armadillo NetworkManager[832]: <info>  [1478193657.6098] audit: op="connection-update" uuid="e7436e3e-c854-4456-9713-bfc8a608e136" name="ether" args="connection.timestamp" pid=2755 uid=0 result="success"
Nov  4 02:21:11 armadillo NetworkManager[832]: <info>  [1478193671.6620] audit: op="connection-activate" uuid="21b87e2f-5738-46d6-bad5-5562cb44a0d4" name="gsm-ttyUSB2" result="fail" reason="No suitable device found for this connection."
Nov  4 02:24:02 armadillo ModemManager[655]: <info>  logging: level 'DEBUG'
Nov  4 02:24:28 armadillo NetworkManager[832]: <info>  [1478193868.2811] audit: op="connection-activate" uuid="21b87e2f-5738-46d6-bad5-5562cb44a0d4" name="gsm-ttyUSB2" result="fail" reason="No suitable device found for this connection."
Nov  4 02:24:31 armadillo ModemManager[655]: <debug> loading signal quality...
Nov  4 02:24:31 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 2 (open)
Nov  4 02:24:31 armadillo ModemManager[655]: <debug> (ttyACM0): --> 'AT+CSQ<CR>'
Nov  4 02:24:31 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>+CSQ: 27,99<CR><LF>'
Nov  4 02:24:31 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>OK<CR><LF>'
Nov  4 02:24:31 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 1 (close)
Nov  4 02:24:31 armadillo ModemManager[655]: <debug> Modem /org/freedesktop/ModemManager1/Modem/0: signal quality updated (87)
Nov  4 02:25:01 armadillo ModemManager[655]: <debug> loading signal quality...
Nov  4 02:25:01 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 2 (open)
Nov  4 02:25:01 armadillo ModemManager[655]: <debug> (ttyACM0): --> 'AT+CSQ<CR>'
Nov  4 02:25:01 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>+CSQ: 31,99<CR><LF>'
Nov  4 02:25:01 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>OK<CR><LF>'
Nov  4 02:25:01 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 1 (close)
Nov  4 02:25:01 armadillo ModemManager[655]: <debug> Modem /org/freedesktop/ModemManager1/Modem/0: signal quality updated (100)
Nov  4 02:25:31 armadillo ModemManager[655]: <debug> loading signal quality...
Nov  4 02:25:31 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 2 (open)
Nov  4 02:25:31 armadillo ModemManager[655]: <debug> (ttyACM0): --> 'AT+CSQ<CR>'
Nov  4 02:25:31 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>+CSQ: 31,99<CR><LF>'
Nov  4 02:25:31 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>OK<CR><LF>'
Nov  4 02:25:31 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 1 (close)
Nov  4 02:25:31 armadillo ModemManager[655]: <debug> Modem /org/freedesktop/ModemManager1/Modem/0: signal quality updated (100)
Nov  4 02:26:01 armadillo ModemManager[655]: <debug> loading signal quality...
Nov  4 02:26:01 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 2 (open)
Nov  4 02:26:01 armadillo ModemManager[655]: <debug> (ttyACM0): --> 'AT+CSQ<CR>'
Nov  4 02:26:01 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>+CSQ: 28,99<CR><LF><CR><LF>OK<CR><LF>'
Nov  4 02:26:01 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 1 (close)
Nov  4 02:26:01 armadillo ModemManager[655]: <debug> Modem /org/freedesktop/ModemManager1/Modem/0: signal quality updated (90)
Nov  4 02:26:31 armadillo ModemManager[655]: <debug> loading signal quality...
Nov  4 02:26:31 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 2 (open)
Nov  4 02:26:31 armadillo ModemManager[655]: <debug> (ttyACM0): --> 'AT+CSQ<CR>'
Nov  4 02:26:31 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>+CSQ: 31,99<CR><LF><CR><LF>OK<CR><LF>'
Nov  4 02:26:31 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 1 (close)
Nov  4 02:26:31 armadillo ModemManager[655]: <debug> Modem /org/freedesktop/ModemManager1/Modem/0: signal quality updated (100)
Nov  4 02:27:01 armadillo ModemManager[655]: <debug> loading signal quality...
Nov  4 02:27:01 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 2 (open)
Nov  4 02:27:01 armadillo ModemManager[655]: <debug> (ttyACM0): --> 'AT+CSQ<CR>'
Nov  4 02:27:01 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>+CSQ: 31,99<CR><LF>'
Nov  4 02:27:01 armadillo ModemManager[655]: <debug> (ttyACM0): <-- '<CR><LF>OK<CR><LF>'
Nov  4 02:27:01 armadillo ModemManager[655]: <debug> (ttyACM0) device open count is 1 (close)
Nov  4 02:27:01 armadillo ModemManager[655]: <debug> Modem /org/freedesktop/ModemManager1/Modem/0: signal quality updated (100)