VPN 在 OSX 和 Windows 10 上运行完美，但在 ubuntu 上却不行
VPN 在 ubuntu 上使用阶段 1 算法连接：3des-sha1-modp1024 阶段 2 算法：3des-sha1
10 秒后断开连接并显示以下信息
xl2tpd[12406]: message_type_avp: message type 6 (Hello)
xl2tpd[12406]: control_finish: message type is Hello(6). Tunnel is 57299, call is 0.
xl2tpd[12406]: check_control: Received out of order control packet on tunnel 57299 (got 2, expected 3)
xl2tpd[12406]: handle_packet: bad control packet!
xl2tpd[12406]: network_thread: bad packet
xl2tpd[12406]: check_control: Received out of order control packet on tunnel 57299 (got 2, expected 3)
xl2tpd[12406]: handle_packet: bad control packet!
xl2tpd[12406]: network_thread: bad packet
xl2tpd[12406]: check_control: Received out of order control packet on tunnel 57299 (got 2, expected 3)
xl2tpd[12406]: handle_packet: bad control packet!
xl2tpd[12406]: network_thread: bad packet
xl2tpd[12406]: check_control: Received out of order control packet on tunnel 57299 (got 2, expected 3)
xl2tpd[12406]: handle_packet: bad control packet!
xl2tpd[12406]: network_thread: bad packet
xl2tpd[12406]: Maximum retries exceeded for tunnel 39703. Closing.
xl2tpd[12406]: Terminating pppd: sending TERM signal to pid 12407
xl2tpd[12406]: Connection 57299 closed to [X.X.X.X], port 1701 (Timeout)
xl2tpd[12406]: message_type_avp: message type 4 (Stop-Control-Connection-Notification)
xl2tpd[12406]: assigned_tunnel_avp: using peer's tunnel 57299
xl2tpd[12406]: result_code_avp: peer closing for reason 1 (General request to clear control connection), error = 0 (Timeout)
xl2tpd[12406]: control_finish: message type is Stop-Control-Connection-Notification(4). Tunnel is 57299, call is 0.
xl2tpd[12406]: control_finish: Connection closed to [X.X.X.X], port 1701 (Timeout), Local: 39703, Remote: 57299
xl2tpd[12406]: build_fdset: closing down tunnel 39703
xl2tpd[12406]: Can not find tunnel 39703 (refhim=0)
xl2tpd[12406]: network_thread: unable to find call or tunnel to handle packet. call = 0, tunnel = 39703 Dumping.
xl2tpd[12406]: Can not find tunnel 39703 (refhim=0)
xl2tpd[12406]: network_thread: unable to find call or tunnel to handle packet. call = 0, tunnel = 39703 Dumping.
nm-l2tp[12257] <info> Terminated xl2tpd daemon with PID 12406.
xl2tpd[12406]: death_handler: Fatal signal 15 received
Stopping strongSwan IPsec...
** Message: 19:27:49.639: ipsec shut down
nm-l2tp[12257] <warn> xl2tpd exited with error code 1
Stopping strongSwan IPsec failed: starter is not running
请指教