Public bug reported:
Ubuntu 26.04 with pppd 2.5.2 cannot establish a PPTP VPN connection to a
Windows Server 2019 RRAS server.
Environment:
- Ubuntu 26.04
- pppd 2.5.2
- pptp-linux 1.10.0
- Windows Server 2019 RRAS (Version 1809, Build 17763.9020)
The connection sequence is:
- PPTP tunnel established
- MS-CHAPv2 authentication succeeds
- Connection terminates immediately with:
CHAP authentication succeeded
MPPE required but peer negotiation failed
The same VPN account and password connect successfully from Windows 11.
Tried:
- require-mppe
- require-mppe-128
- nomppe-stateful
- NetworkManager PPTP plugin
- pptp-linux command line
The result is always the same.
This appears to be an interoperability problem between pppd 2.5.2 and
Windows Server 2019 RRAS MPPE negotiation.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: ppp 2.5.2-1+1.2
ProcVersionSignature: Ubuntu 7.0.0-28.28-generic 7.0.12
Uname: Linux 7.0.0-28-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Mon Aug 3 02:04:49 2026
InstallationDate: Installed on 2026-07-25 (8 days ago)
InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1)
SourcePackage: ppp
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: ppp (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2162691
Title:
PPTP VPN fails with "MPPE required but peer negotiation failed"
against Windows Server 2019 RRAS
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