To connect using legacy pptp:
sudo apt install pptp-linux
Issue:
MPPE required, but MS-CHAP[v2] nor EAP-TLS auth are performed. sent [LCP TermReq id=0x3 "MPPE required but not available"] rcvd [LCP EchoReq id=0x0 magic=0x5dd9b546] rcvd [LCP TermReq id=0x3 "peer refused to authenticate"]
Solution:
# client server secret IP address john provider "secret" *