Ubuntu – PPTP VPN randomly disconnects

20.04network-managerpptppptpdvpn

My PPTP VPN works fine on Windows and Android.
On Android and Windows, no specific configuration is needed only I need to check PPP encryption(MPPE).

But on Ubuntu 20.04 it disconnects randomly after a period of time.

Best Answer

I found the answer here: Ubuntu 14 pptp client disconnects frequently.

I had to use on the client.

sudo ifconfig wlp3s0 mtu 1400
sudo ifconfig ppp0 mtu 1300

This could be investigated by reading syslog errors:

pouria@pouria-pc:~$ cat /var/log/syslog | grep pptp | grep long
May 31 09:36:11 pouria-pc pptp[18156]: nm-pptp-service-18147 warn[decaps_gre:pptp_gre.c:352]: short read (-1): Message too long
May 31 09:47:14 pouria-pc pptp[18617]: nm-pptp-service-18609 warn[decaps_gre:pptp_gre.c:352]: short read (-1): Message too long
May 31 09:57:18 pouria-pc pptp[19439]: nm-pptp-service-19430 warn[decaps_gre:pptp_gre.c:352]: short read (-1): Message too long
May 31 10:07:21 pouria-pc pptp[20790]: nm-pptp-service-20781 warn[decaps_gre:pptp_gre.c:352]: short read (-1): Message too long
May 31 10:17:57 pouria-pc pptp[21003]: nm-pptp-service-20994 warn[decaps_gre:pptp_gre.c:352]: short read (-1): Message too long
May 31 11:16:36 pouria-pc pptp[23730]: nm-pptp-service-23718 warn[decaps_gre:pptp_gre.c:352]: short read (-1): Message too long

By setting mtu we are telling the wlan to use smaller messages.

I wonder why users of other operating systems don't have to configure their WLAN message size to use the simplest form of VPN.