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I have configured VPN (PPTP) connection (configured as in screenshot) and I'm experiencing this issue (ubuntu 12.10):

The connection works fine, I can browse web and access local content, however after sometime it freeze ( also ping a local address doesn't give answer anymore ) and the only way to re-enable the connection is to stop it and restart it

I have noticed in var/log/syslog that when the connection freezes those messages starts to be logged:

 pppd[8268]: Protocol-Reject for unsupported protocol 'IP6 Header Compression' (0x4f)
 pppd[8268]: Protocol-Reject for unsupported protocol 0x1c18
 pppd[8268]: Protocol-Reject for unsupported protocol 0xb9
 pppd[8268]: Protocol-Reject for unsupported protocol 'RTP IPHC Full Header' (0x61)
 pppd[8268]: Protocol-Reject for unsupported protocol 'KNX Bridging Control Protocol' 

The issue looks like this one:


And here looks as well documented http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=427825

Settings :


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Does this solution apply to your case? –  harrymc Jan 28 '13 at 15:08
looking into it, I will let you know –  Francesco Jan 28 '13 at 16:51
(1) Do you need IPv6 over PPTP? Disable IPv6 if not needed. (2) Uncheck MSCHAP. Let me know if that works and move to answer. –  John Siu Jan 28 '13 at 17:16
I have fixed it upgrading pptp-linux package with the one on debian sid ... but now it is back again –  Francesco Jun 15 '13 at 4:48

1 Answer 1

According to http://pptpclient.sourceforge.net/howto-diagnosis.phtml#connections_freeze it could be an MTU issue, so try setting your MTU to a lower value (e.g. 1400).

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