It hangs at the end and I can see in /var/log/messages “modem-manager: (net/tun0) could not get port’s parent device” and then eventually “withdrawing workstation service for tun0”.
My settings are correct and other people seem to be able to connect.
I am not using KNetworkManager because of an issue on my machine regarding rfkill.
As to resolv.conf being regenerated it depends on your set up. Sometimes it gets regenerated and sometimes doesn’t.
AFAIK rfkill has got nothing to do with knetworkmanager. Rfkill lets You kill your radio on WiFi and knetworkmanager is a KDE app to control NetworkManager.