I have encounter 1 particular problem in setting up VPN using PPTP, the log file shows:
GRE: read(fd=6,buffer=611860,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs
I solved this by commenting out this line in /etc/ppp/options.pptpd:
#require-mppe-128
This allows Linux user to be able to connect VPN by default settings, otherwise Linux user need to tick “Use Point-to-Point encryption” and select 128bit encryption.
On the Internet, there is a saying that comment out “logwtmp” could be a way of solving this case. This doesn’t work for me.