Comment 2 for bug 1496869

This https://bugs.launchpad.net/fuel/5.1.x/+bug/1425901 seems to be related. Problem was happening when the bond is configured and MACs were reported as equal for all interfaces included in bond. Nailgun loose interfaces in that case. Another problem https://bugs.launchpad.net/fuel/+bug/1425907 : if some interface is not present in Nailgun agent's data for some time and that interface has some networks mapped to it, those networks became unmapped to particular node and user cannot remap them again. Only node removal and readding the node to environment helps in that case.