Disconnected, Red vs Blue - whats the difference?

I've just disabled the HA interface which sent the Disconnected state to RED, which seems to mean that it cannot communicate with its peer. When I turned this back on, it eventually went BLUE, so it could communicate but it couldn't sync. That seems to be the difference with the colour. Issue still exists with the port 6699 being unavailable on one of the devices. As these are VE's we're going to try moving the one with the problem to a different host to force and ARP which will hopefully clear any issues with ports being held open.