Ubuntu 18.04 Sierra Wireless EM7455 调制解调器管理器 v1.6.8
尝试使用内置调制解调器进行连接会导致系统日志中出现此错误，并且 GUI 中会出现“网络连接激活失败”
May 30 22:22:45 T470s NetworkManager[1320]: <info> [1527682965.5616] device (cdc-wdm0): Activation: starting connection 'Optus Mobile Internet' (0bf40498-37c8-41f3-8518-8318ed072033)
May 30 22:22:45 T470s NetworkManager[1320]: <info> [1527682965.5618] audit: op="connection-activate" uuid="0bf40498-37c8-41f3-8518-8318ed072033" name="Optus Mobile Internet" pid=5708 uid=1000 result="success"
May 30 22:22:45 T470s NetworkManager[1320]: <info> [1527682965.5622] device (cdc-wdm0): state change: disconnected -> prepare (reason 'none', sys-iface-state: 'managed')
May 30 22:22:45 T470s ModemManager[1335]: <info> Simple connect started...
May 30 22:22:45 T470s ModemManager[1335]: <info> Simple connect state (4/8): Wait to get fully enabled
May 30 22:22:45 T470s ModemManager[1335]: <info> Simple connect state (5/8): Register
May 30 22:22:45 T470s ModemManager[1335]: <info> Simple connect state (6/8): Bearer
May 30 22:22:45 T470s ModemManager[1335]: <info> Simple connect state (7/8): Connect
May 30 22:22:45 T470s ModemManager[1335]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: state changed (registered -> connecting)
May 30 22:22:45 T470s NetworkManager[1320]: <info> [1527682965.5896] modem["cdc-wdm0"]: modem state changed, 'registered' --> 'connecting' (reason: user-requested)
May 30 22:22:47 T470s ModemManager[1335]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: 3GPP Registration state changed (home -> unknown)
May 30 22:22:47 T470s ModemManager[1335]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: 3GPP Registration state changed (unknown -> searching)
May 30 22:22:50 T470s ModemManager[1335]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: state changed (connecting -> searching)
May 30 22:22:50 T470s NetworkManager[1320]: <info> [1527682970.0241] modem["cdc-wdm0"]: modem state changed, 'connecting' --> 'searching' (reason: user-requested)
May 30 22:22:50 T470s NetworkManager[1320]: <warn> [1527682970.0243] modem-broadband[cdc-wdm0]: failed to connect modem: Failure
May 30 22:22:50 T470s NetworkManager[1320]: <info> [1527682970.0244] device (cdc-wdm0): state change: prepare -> failed (reason 'unknown', sys-iface-state: 'managed')
May 30 22:22:50 T470s NetworkManager[1320]: <warn> [1527682970.0261] device (cdc-wdm0): Activation: failed for connection 'Optus Mobile Internet'
May 30 22:22:50 T470s NetworkManager[1320]: <info> [1527682970.0276] device (cdc-wdm0): state change: failed -> disconnected (reason 'none', sys-iface-state: 'managed')
May 30 22:22:51 T470s ModemManager[1335]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: 3GPP Registration state changed (searching -> registering)
May 30 22:22:51 T470s ModemManager[1335]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: 3GPP Registration state changed (registering -> home)
May 30 22:22:51 T470s ModemManager[1335]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: state changed (searching -> registered)
May 30 22:22:51 T470s NetworkManager[1320]: <info> [1527682971.7231] modem["cdc-wdm0"]: modem state changed, 'searching' --> 'registered' (reason: unknown)