Looking at calibre log I see:
- Calibre connects successfully to the wireless device network socket.
- Calibre did not see any attempt to connect on that socket.
- Calibre did not see any "are you there" broadcasts.
Looking at the CC log I see:
- CC "sees" calibre's MDNS (bonjour) advertisements.
- Sometimes when connecting, CC "sees" multiple bonjour advertisements. This shouldn't happen. Do you have multiple instances of calibre running?
- Starting at 2018-01-03 09:25:32, CC sees calibre's wireless device UDP broadcast response but fails to connect (TCP) to the supplied IP address. This strongly implies a firewall problem.
- Some connection attempts fail with "no route to host". Others fail with a timeout. I don't know why that would happen.
Given the above, all I can say with certainty is that something is preventing CC from connecting to calibre. Exactly what the "something" is I cannot say, but it "smells" like a firewall somewhere.
Questions:
- Are TCP connections to port 9091 allowed through your firewall?
- Does your home router have any filtering set up?
- What happens if you turn off the content server in calibre then change the WD port to 8080?
- Do you have any intrusion detection software running on your Linux box?
- I note from your tcpdump that port 9091 is identified as xmltec-xmlmail. Do you have any sort of auto-start based on port numbers? What happens if you set the calibre WD port to something bizarre (and unassigned) such as 14802?