pptpd - Centos7 pptp 连接云梯VPN 失败

`pptpsetup --create MYVPN --server xxx.xxx.xxx.xxx --username username --password password -- start`

失败log：

Nov 24 18:08:52 localhost pppd[8169]: pppd 2.4.5 started by wonbin, uid 0
Nov 24 18:08:52 localhost pppd[8169]: Using interface ppp0
Nov 24 18:08:52 localhost pppd[8169]: Connect: ppp0 <--> /dev/pts/2
Nov 24 18:08:52 localhost NetworkManager[843]:   (ppp0): new Generic device (driver: 'unknown' ifindex: 13)
Nov 24 18:08:52 localhost NetworkManager[843]:   (ppp0): exported as /org/freedesktop/NetworkManager/Devices/12
Nov 24 18:08:52 localhost pptp[8170]: anon log[main:pptp.c:333]: The synchronous pptp option is NOT activated
Nov 24 18:08:52 localhost pptp[8177]: anon log[ctrlp_rep:pptp_ctrl.c:254]: Sent control packet type is 1 'Start-Control-Connection-Request'
Nov 24 18:08:52 localhost pptp[8177]: anon log[ctrlp_disp:pptp_ctrl.c:754]: Received Start Control Connection Reply
Nov 24 18:08:52 localhost pptp[8177]: anon log[ctrlp_disp:pptp_ctrl.c:788]: Client connection established.
Nov 24 18:08:53 localhost pptp[8177]: anon log[ctrlp_rep:pptp_ctrl.c:254]: Sent control packet type is 7 'Outgoing-Call-Request'
Nov 24 18:08:53 localhost pptp[8177]: anon log[ctrlp_disp:pptp_ctrl.c:873]: Received Outgoing Call Reply.
Nov 24 18:08:53 localhost pptp[8177]: anon log[ctrlp_disp:pptp_ctrl.c:912]: Outgoing call established (call ID 0, peer's call ID 60800).

Nov 24 18:09:23 localhost pppd[8169]: LCP: timeout sending Config-Requests
Nov 24 18:09:23 localhost pppd[8169]: Connection terminated.
Nov 24 18:09:23 localhost avahi-daemon[816]: Withdrawing workstation service for ppp0.
Nov 24 18:09:23 localhost gnome-session: JS LOG: Removing a network device that was not added
Nov 24 18:09:23 localhost pppd[8169]: Modem hangup
Nov 24 18:09:23 localhost pptp[8170]: anon warn[decaps_hdlc:pptp_gre.c:217]: short read (-1): Input/output error
Nov 24 18:09:23 localhost pptp[8170]: anon warn[decaps_hdlc:pptp_gre.c:229]: pppd may have shutdown, see pppd log
Nov 24 18:09:23 localhost pptp[8177]: anon log[callmgr_main:pptp_callmgr.c:242]: Closing connection (unhandled)
Nov 24 18:09:23 localhost pptp[8177]: anon log[ctrlp_rep:pptp_ctrl.c:254]: Sent control packet type is 12 'Call-Clear-Request'
Nov 24 18:09:23 localhost pptp[8177]: anon log[call_callback:pptp_callmgr.c:81]: Closing connection (call state)
Nov 24 18:09:23 localhost pppd[8169]: Exit.

请问是哪方面出了问题