I configured my VPN server on my swisscom internet-box 2 as indicated in this documentation
enabling the VPN server:
creating VPN credentials and shared key:
Connection from my Iphone worked immediately, but for my Fedora laptop it was another story.
several discussions link1 link2 helped me to solve my issue with this error message:
pppd: EAP: Identity prompt "Name"
pppd: EAP: peer reports authentication failure
The correct settings for me:
VPN connection with credentials information:
disable FPS in IPsec Settings:
select only MSCHAPv2 as authentication method in PPP Settings: