VPN服务连接失败，因为VPN服务无法启动

我正在尝试在Ubuntu上连接到我的大学VPN。不幸的是，他们没有提供关于Linux（我在Ubuntu 16.04上）VPN设置的任何指导，仅是Windows和Mac，因此我试图从他们提供给他们的信息中进行连接。

这是他们的在线指南-https: //www.stir.ac.uk/is/student/it/connect/off-campus/

根据Mac安装指南，它指出：

“ VPN类型：基于IPsec的L2TP” ..所以我已经运行sudo apt-get install network-manager-l2tp-gnome，重新启动了Ubuntu，现在我可以选择创建第2层隧道协议（L2TP）连接。

我已经按照他们的指示输入了网关和用户名。当他们也请求“通过IPsec”时，我已经选中了“ IPsec设置...”>“启用到L2TP主机的IPsec隧道”框，因此我也在“预共享密钥”框中输入了“秘密”。顺便说一句，我也尝试在设置这些参数之前先进行连接，但是它不起作用，现在我也输入了它们，因此不起作用。

如果有帮助，请参阅以下日志sudo tail -f /var/log/syslog：

Mar  1 15:29:32 martyn-Lenovo-B590 NetworkManager[954]: <info>  [1519918172.6221] audit: op="connection-activate" uuid="9f1fcb5e-7d9b-41e2-9637-2a9545283b10" name="UoS VPN" pid=2301 uid=1000 result="success"
Mar  1 15:29:32 martyn-Lenovo-B590 NetworkManager[954]: <info>  [1519918172.6310] vpn-connection[0x27291e0,9f1fcb5e-7d9b-41e2-9637-2a9545283b10,"UoS VPN",0]: Started the VPN service, PID 4452
Mar  1 15:29:32 martyn-Lenovo-B590 NetworkManager[954]: <info>  [1519918172.6452] vpn-connection[0x27291e0,9f1fcb5e-7d9b-41e2-9637-2a9545283b10,"UoS VPN",0]: Saw the service appear; activating connection
Mar  1 15:29:32 martyn-Lenovo-B590 gnome-session[1999]: Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.
Mar  1 15:29:37 martyn-Lenovo-B590 NetworkManager[954]: <info>  [1519918177.6835] keyfile: update /etc/NetworkManager/system-connections/UoS VPN (9f1fcb5e-7d9b-41e2-9637-2a9545283b10,"UoS VPN")
Mar  1 15:29:37 martyn-Lenovo-B590 NetworkManager[954]: <info>  [1519918177.6915] vpn-connection[0x27291e0,9f1fcb5e-7d9b-41e2-9637-2a9545283b10,"UoS VPN",0]: VPN connection: (ConnectInteractive) reply received
Mar  1 15:29:37 martyn-Lenovo-B590 NetworkManager[954]: nm-l2tp[4452] <info>  ipsec enable flag: yes
Mar  1 15:29:37 martyn-Lenovo-B590 NetworkManager[954]: ** Message: Check port 1701
Mar  1 15:29:37 martyn-Lenovo-B590 NetworkManager[954]: ** Message: Can't bind to port 1701
Mar  1 15:29:37 martyn-Lenovo-B590 NetworkManager[954]: nm-l2tp[4452] <warn>  L2TP port 1701 is busy, using ephemeral.
Mar  1 15:29:37 martyn-Lenovo-B590 NetworkManager[954]: nm-l2tp[4452] <info>  starting ipsec
Mar  1 15:29:37 martyn-Lenovo-B590 NetworkManager[954]: Stopping strongSwan IPsec failed: starter is not running
Mar  1 15:29:39 martyn-Lenovo-B590 NetworkManager[954]: Starting strongSwan 5.3.5 IPsec [starter]...
Mar  1 15:29:39 martyn-Lenovo-B590 NetworkManager[954]: Loading config setup
Mar  1 15:29:39 martyn-Lenovo-B590 NetworkManager[954]: Loading conn '9f1fcb5e-7d9b-41e2-9637-2a9545283b10'
Mar  1 15:29:39 martyn-Lenovo-B590 NetworkManager[954]: found netkey IPsec stack
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[DMN] Starting IKE charon daemon (strongSwan 5.3.5, Linux 4.4.0-116-generic, x86_64)
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[CFG] loading ca certificates from '/etc/ipsec.d/cacerts'
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[CFG] loading aa certificates from '/etc/ipsec.d/aacerts'
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[CFG] loading ocsp signer certificates from '/etc/ipsec.d/ocspcerts'
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[CFG] loading attribute certificates from '/etc/ipsec.d/acerts'
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[CFG] loading crls from '/etc/ipsec.d/crls'
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[CFG] loading secrets from '/etc/ipsec.secrets'
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[CFG] loading secrets from '/etc/ipsec.d/nm-l2tp-ipsec-9f1fcb5e-7d9b-41e2-9637-2a9545283b10.secrets'
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[CFG]   loaded IKE secret for %any
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[LIB] loaded plugins: charon test-vectors aes rc2 sha1 sha2 md4 md5 random nonce x509 revocation constraints pubkey pkcs1 pkcs7 pkcs8 pkcs12 pgp dnskey sshkey pem openssl fips-prf gmp agent xcbc hmac gcm attr kernel-netlink resolve socket-default connmark stroke updown
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[LIB] dropped capabilities, running as uid 0, gid 0
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 00[JOB] spawning 16 worker threads
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 13[CFG] received stroke: add connection '9f1fcb5e-7d9b-41e2-9637-2a9545283b10'
Mar  1 15:29:39 martyn-Lenovo-B590 charon: 13[CFG] added configuration '9f1fcb5e-7d9b-41e2-9637-2a9545283b10'
Mar  1 15:29:40 martyn-Lenovo-B590 charon: 01[CFG] rereading secrets
Mar  1 15:29:40 martyn-Lenovo-B590 charon: 01[CFG] loading secrets from '/etc/ipsec.secrets'
Mar  1 15:29:40 martyn-Lenovo-B590 charon: 01[CFG] loading secrets from '/etc/ipsec.d/nm-l2tp-ipsec-9f1fcb5e-7d9b-41e2-9637-2a9545283b10.secrets'
Mar  1 15:29:40 martyn-Lenovo-B590 charon: 01[CFG]   loaded IKE secret for %any
Mar  1 15:29:40 martyn-Lenovo-B590 NetworkManager[954]: nm-l2tp[4452] <info>  Spawned ipsec up script with PID 4531.
Mar  1 15:29:40 martyn-Lenovo-B590 charon: 11[CFG] received stroke: initiate '9f1fcb5e-7d9b-41e2-9637-2a9545283b10'
Mar  1 15:29:40 martyn-Lenovo-B590 charon: 07[IKE] initiating Main Mode IKE_SA 9f1fcb5e-7d9b-41e2-9637-2a9545283b10[1] to 139.153.12.200
Mar  1 15:29:40 martyn-Lenovo-B590 charon: 07[ENC] generating ID_PROT request 0 [ SA V V V V ]
Mar  1 15:29:40 martyn-Lenovo-B590 charon: 07[NET] sending packet: from 192.168.1.134[500] to 139.153.12.200[500] (248 bytes)
Mar  1 15:29:44 martyn-Lenovo-B590 charon: 02[IKE] sending retransmit 1 of request message ID 0, seq 1
Mar  1 15:29:44 martyn-Lenovo-B590 charon: 02[NET] sending packet: from 192.168.1.134[500] to 139.153.12.200[500] (248 bytes)
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: nm-l2tp[4452] <warn>  Timeout trying to establish IPsec connection
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: nm-l2tp[4452] <info>  Terminating ipsec script with PID 4531.
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: Stopping strongSwan IPsec...
Mar  1 15:29:50 martyn-Lenovo-B590 charon: 00[DMN] signal of type SIGINT received. Shutting down
Mar  1 15:29:50 martyn-Lenovo-B590 charon: 00[IKE] destroying IKE_SA in state CONNECTING without notification
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: initiating Main Mode IKE_SA 9f1fcb5e-7d9b-41e2-9637-2a9545283b10[1] to 139.153.12.200
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: generating ID_PROT request 0 [ SA V V V V ]
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: sending packet: from 192.168.1.134[500] to 139.153.12.200[500] (248 bytes)
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: sending retransmit 1 of request message ID 0, seq 1
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: sending packet: from 192.168.1.134[500] to 139.153.12.200[500] (248 bytes)
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: destroying IKE_SA in state CONNECTING without notification
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: nm-l2tp[4452] <warn>  Could not establish IPsec tunnel.
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: (nm-l2tp-service:4452): GLib-GIO-CRITICAL **: g_dbus_method_invocation_take_error: assertion 'error != NULL' failed
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: <info>  [1519918190.9294] vpn-connection[0x27291e0,9f1fcb5e-7d9b-41e2-9637-2a9545283b10,"UoS VPN",0]: VPN plugin: state changed: stopped (6)
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: <info>  [1519918190.9315] vpn-connection[0x27291e0,9f1fcb5e-7d9b-41e2-9637-2a9545283b10,"UoS VPN",0]: VPN plugin: state change reason: unknown (0)
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: <info>  [1519918190.9339] vpn-connection[0x27291e0,9f1fcb5e-7d9b-41e2-9637-2a9545283b10,"UoS VPN",0]: VPN service disappeared
Mar  1 15:29:50 martyn-Lenovo-B590 NetworkManager[954]: <warn>  [1519918190.9360] vpn-connection[0x27291e0,9f1fcb5e-7d9b-41e2-9637-2a9545283b10,"UoS VPN",0]: VPN connection: failed to connect: 'Message recipient disconnected from message bus without replying'

我确实尝试使用Google搜索某些错误，但没有发现任何似乎有用的东西，尽管这有点麻烦。

我有什么想念的吗？提前致谢。