Hi, I'm seeing a very similar problem to the thread "Sporadic networking issues" [1]. In our setup, some TCP operations receive unexpected RST packets when executed on the guest. I can see these RST packets via wireshark but can't explain their source. We originally uncovered this when some 'git clone' operations failed with "Broken Pipe" in the guests. I've been able to reproduce the same failures using scp and 'svn checkout'. The failure occurs 80-90% of the time and 'svn checkout' seems to be the quickest to fail. The same operations on the host are always successful. My setup is a Lucid amd64 host with two guests (Lucid and Hardy, both i386, using kvm). Networking is configured as described in "Routed network config". One anomoly I notice is that our configuration is missing the 'mode' and 'dev' attributes of the 'forward' node. Not sure if that makes a difference, especially since networking seems to mostly work. I've tried this with both virtio and e1000 drivers with no difference. I tried Jeremy's suggestion to limit the host to start a single guest but that did not seem to have an impact. One thing I wonder is if I'm resetting the libvirt correctly to make this change. I did not reboot the host, but I did shutdown the guests, shutdown the default network, verified that no kvm was running and no tap/bridge devices existed, undefined the Hardy domain, then restarted the default network and started the Lucid kvm. Does that sound correct? Anyone have suggestions for further debugging or pointer(s) to existing related bugs? My search didn't turn up anything obvious. I'm very eager to resolve this issue since it's blocking our ability to use the VMs. Thanks, brian 1 - https://www.redhat.com/archives/libvirt-users/2010-August/msg00012.html