Note, please back up the system, please back up the system, please back up the system. Say important things three times pptp for macOS Catalina
Mac OS Catalina completely disables VPN of PPTP protocol, but we can overwrite or add these three files
/usr/local/bin/pptp
/System/Library/Extensions/PPTP.ppp
/System/Library/Extensions/PPP.kext
First of all, your system version must be below 10.15.3. Someone in the forum said that the higher version system could not succeed.
After copying, try to give the driver file permission
sudo chmod -R 755 /System/Library/Extensions
sudo chown -R root:wheel /System/Library/Extensions
If you still can't connect, try connecting CPN manually in the terminal
sudo pppd call xxxxx