I try to setup a PPTP VPN server on Centos 7 and from client a router Vodafone Station (Firmware 5.4.8.1.316.1.21) On c7 I have install this: [root at s-virt tmp]# rpm -q pptpd ppppptpd-1.4.0-2.el7.x86_64ppp-2.4.5- 33.el7.x86_64 and setup all file and firewall like howto say.This now is my config: /etc/pptpd.conf:option /etc/ppp/options.pptpd/etc/pptpd.conf:logwtmp/etc/pptpd.conf:localip 192.168.11.1/etc/pptpd.conf:remoteip 192.168.11.100- 109/etc/ppp/options.pptpd:name pptpd/etc/ppp/options.pptpd:refuse- pap/etc/ppp/options.pptpd:refuse-chap/etc/ppp/options.pptpd:refuse- mschap/etc/ppp/options.pptpd:require-mschap- v2/etc/ppp/options.pptpd:require-mppe- 128/etc/ppp/options.pptpd:lock/etc/ppp/options.pptpd:nobsdcomp /etc/ppp /options.pptpd:novj/etc/ppp/options.pptpd:novjccomp/etc/ppp/options.ppt pd:nologfd/etc/ppp/chap-secrets:myuser pptpd mypass * The connection from V.S. router to my c7 server work:mar 26 12:50:28 s- virt.ansaldi.loc pptpd[26782]: CTRL: Client x.x.x.x control connection startedmar 26 12:50:28 s-virt.ansaldi.loc pptpd[26782]: CTRL: Starting call (launching pppd, opening GRE)mar 26 12:50:28 s-virt.ansaldi.loc pppd[26783]: Plugin /usr/lib64/pptpd/pptpd-logwtmp.so loaded.mar 26 12:50:28 s-virt.ansaldi.loc pppd[26783]: pppd 2.4.5 started by root, uid 0mar 26 12:50:28 s-virt.ansaldi.loc pppd[26783]: Using interface ppp0mar 26 12:50:28 s-virt.ansaldi.loc pppd[26783]: Connect: ppp0 <--> /dev/pts/19mar 26 12:50:28 s-virt.ansaldi.loc NetworkManager[1026]: <info> [1522061428.6946] manager: (ppp0): new Generic device (/org/freedesktop/NetworkManager/Devices/40)mar 26 12:50:28 s- virt.ansaldi.loc pppd[26783]: peer from calling number x.x.x.x authorizedmar 26 12:50:31 s-virt.ansaldi.loc pppd[26783]: MPPE 128-bit stateless compression enabledmar 26 12:50:34 s-virt.ansaldi.loc pppd[26783]: local IP address 192.168.11.1mar 26 12:50:34 s- virt.ansaldi.loc pppd[26783]: remote IP address 192.168.11.100 But when I try to connect from a client (through the V. S. router) to my server via VPN, or ping it, on 4 ping only two work, and into log of server I see this error when the ping fail. > mar 26 12:00:50 s-virt.ansaldi.loc kernel: mppe_decompress[0]: > FLUSHED bit not set in stateless mode! Someone have some suggest to resolve this problem ? Many thanks -- Dario Lesca (inviato dal mio Linux Fedora 27 Workstation)