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I'm using 16.04 LTS amd64. My pptp connection used to be fine a few days ago but from yesterday on it malfunctions. It connects with no problem but shortly within 3 or 4 minutes drops the connections.

Here's the syslog (stating exactly at the moment when it fails):

May 29 11:52:14 ABFORCE pptp[11219]: nm-pptp-service-11187 log[pptp_handle_timer:pptp_ctrl.c:1105]: closing control connection due to missing echo reply
May 29 11:52:14 ABFORCE pptp[11219]: nm-pptp-service-11187 log[ctrlp_rep:pptp_ctrl.c:259]: Sent control packet type is 12 'Call-Clear-Request'
May 29 11:52:14 ABFORCE pptp[11219]: nm-pptp-service-11187 log[pptp_conn_close:pptp_ctrl.c:461]: Closing PPTP connection
May 29 11:52:14 ABFORCE NetworkManager[1017]: Modem hangup
May 29 11:52:14 ABFORCE pptp[11219]: nm-pptp-service-11187 log[ctrlp_rep:pptp_ctrl.c:259]: Sent control packet type is 3 'Stop-Control-Connection-Request'
May 29 11:52:14 ABFORCE NetworkManager[1017]: ** Message: nm-pptp-ppp-plugin: (nm_phasechange): status 8 / phase 'network'
May 29 11:52:14 ABFORCE NetworkManager[1017]: Connect time 4.0 minutes.
May 29 11:52:14 ABFORCE NetworkManager[1017]: Sent 3646742980 bytes, received 2594786 bytes.
May 29 11:52:14 ABFORCE pptp[11219]: nm-pptp-service-11187 log[call_callback:pptp_callmgr.c:84]: Closing connection (call state)
May 29 11:52:14 ABFORCE pppd[11196]: Modem hangup
May 29 11:52:14 ABFORCE pppd[11196]: Connect time 4.0 minutes.
May 29 11:52:14 ABFORCE pppd[11196]: Sent 3646742980 bytes, received 2594786 bytes.
May 29 11:52:14 ABFORCE NetworkManager[1017]: <error> [1464506534.7838] platform-linux: do-add-ip4-route[19: 0.0.0.0/0 50]: failure 100 (Network is down)
May 29 11:52:14 ABFORCE NetworkManager[1017]: <warn>  [1464506534.7838] default-route: failed to add default route 0.0.0.0/0 via 0.0.0.0 dev 19 metric 50 mss 0 src vpn with effective metric 50
May 29 11:52:14 ABFORCE NetworkManager[1017]: ** Message: nm-pptp-ppp-plugin: (nm_phasechange): status 5 / phase 'establish'
May 29 11:52:14 ABFORCE NetworkManager[1017]: ** Message: nm-pptp-ppp-plugin: (nm_phasechange): status 11 / phase 'disconnect'
May 29 11:52:14 ABFORCE NetworkManager[1017]: Connection terminated.
May 29 11:52:14 ABFORCE pppd[11196]: Connection terminated.
May 29 11:52:14 ABFORCE NetworkManager[1017]: <error> [1464506534.7852] platform-linux: do-change-link[19]: failure changing link: failure 19 (No such device)
May 29 11:52:14 ABFORCE NetworkManager[1017]: <warn>  [1464506534.7852] device (ppp0): failed to disable userspace IPv6LL address handling
May 29 11:52:14 ABFORCE NetworkManager[1017]: ** Message: Terminated ppp daemon with PID 11196.
May 29 11:52:14 ABFORCE NetworkManager[1017]: <error> [1464506534.7856] platform-linux: do-add-ip4-route[19: 0.0.0.0/0 50]: failure 19 (No such device)
May 29 11:52:14 ABFORCE NetworkManager[1017]: <warn>  [1464506534.7856] default-route: failed to add default route 0.0.0.0/0 via 0.0.0.0 dev 19 metric 50 mss 0 src vpn with effective metric 50
May 29 11:52:14 ABFORCE NetworkManager[1017]: <info>  [1464506534.7893] vpn-connection[0x2a17200,26f48d34-ac2b-4db9-ba9e-ef146551580a,"Sharif VPN",19:(ppp0)]: VPN plugin: state changed: stopping (5)
  • network-manager 1.1.93
  • pptp-linux 1.8.0
  • ppp 2.4.7
frogatto
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  • Sorry It's late, you need to change MTU of both ppp0 and your wireless, I wrote a full answer about how to do it here: https://askubuntu.com/questions/1245425/pptp-vpn-randomly-disconnects/1358055#1358055 – SdSaati Aug 15 '21 at 12:19

1 Answers1

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I had exactly the same issue. I searched for a whole day to understand why this happened. In my case, the root cause was caught in syslog in an entry: nm-pptp-service-17364 warn[decaps_gre:pptp_gre.c:347]: short read (-1): Message too long. Apparently the cause was a MTU setting in the WLAN adapter that was too big. By default it is set to automatic.

What I did is that I set it to 1200 and it works just fine.

Hope this helps,

Radu

Radu Crisan
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