There are weird things happening.
First, there seems to be two calibre machines involved, one whose name starts with a G and one whose name starts with an R. I would guess that the 'G' machine is your home machine.
One scenario I see on 2014-08-22:
- 21:58:59: CC attempts to connect to calibre using "automatic". No calibre instance responds
- 22:00:00: CC attempts to connect to the manually-entered IP address 10.0.1.99. That host is not found on the network.
- 22:00:09: again using 10.0.1.99. Fails again.
- 22:01:21: attempt to connect to calibre using automatic. A calibre instance on "G" with IP address 10.0.1.2 responds. CC successfully connects.
The thing that bothers me is that the IP address you manually entered is not the IP address that calibre responds with via automatic connections. Where did you get that IP address? Is it possible that "G" is connected to your network twice?
Another similar scenario on 2014-08-23:
- 12:35:46: successful automatic connect to 10.0.1.2
- 22:42:52: several failed connects
- 22:52:29: failed attempt to connect to manual address 10.0.1.90
- 22:52:42: successful automatic connect to 10.0.1.2.
Something that makes me wonder about your network. CC uses two different techniques to attempt to auto-connect, a broadcast and mDNS (what Apple calls Bonjour). I see mDNS responses from "G" *sometimes*. What is happening to the others? Do you have a very congested network? A complicated cable/wireless setup? Neighbors who might have wireless hubs that interfere with yours? Clearly something on your network is eating those mDNS packets and, frequently, CC's broadcast packets.
Finally, what happens if you manually enter into CC the IP address 10.0.1.2? Do the failures go away?