After upgrading my systems to Fedora 21 I decided to give Firewalld and NetworkManager technologies a try instead of keep relying on iptables and network.service but I now have my doubts.

I have a F21 host with br0 configured with a network-script file to obtain its IP via dhcp (no problems with this), firewalld is running on the host and the guests are using  br0 and dhcp to obtain the IPs from the same source the host/br0 is getting its own IP.

The problem I'm having is that, after some time, packets from the guests are not being forwarded by br0 but I can't quite locate the reason for this. It is not until I restart the guest that everything starts working again (restarting NetworkManager in the guest does not work).

Why br0 stops forwarding packets? What would be the right approach to get this setup working? Should I just forget about Firewalld and NetworkManager by disable them and instead keep using iptables and network.service?

Thanks in advance,