Fedora 21 - pptp vpn error

today, after upgrading to fedora 21 (from 20), my work pptp vpn connection stopped working. looking at journactl, the interesting message was:
: ** (nm-pptp-service:3518): WARNING **: pppd exited with error code 16
After checking around, the problem was with iptables default configuration (the upgrade readded some default rules). Since i don't need a local firewall, I simply disabled it and vpn began to work again.
to temporarily disable it: iptables --flush
to permanently disable id: systemctl disable firewalld