If I disconnect the network cable from the SB2 while playing and then reconnect it a few seconds later (probably > 5s) then it fails to reconnect to SC. A power-on reboot is required to clear the condition. This does not seem to happen every time and may be a factor of the network traffic at the time or the period for which the link is down.

Using a sniffer on the SC host, I first see TCP connect request with a source IP address that is one greater than before (192.168.1.103 -> 192.168.1.104). I see the SYN and SYN ACK but no ACK.  that is, the 3-way packaet exchange does not complete. Then I see repeated SLIM discovery requests and ARP requests for SC. It very much seems like the SB2 is not seeing the replies. My guess is that it still thinks it has address 192.168.1.103.

It has not DHCP'ed for and been given the new IP address, as this is still unallocated (luckily) in the DHCP server.