Apple has made available a small FAQ on its new Thunderbolt Ethernet adapter, which outlines some uses and limitations of the adapter, and also hints at potential troubleshooting for both it and other Thunderbolt devices.
In the FAQ, Apple makes particular note about the daisy-chaining of Thunderbolt devices; each chain can support up to eight devices (including the host computer). While in most cases users will have peripheral devices such as hard drives or I/O controllers attached to their systems, it is also possible to connect multiple computers in the same daisy chain (one use of this is for Target Disk mode). If such a setup is used, then peripheral devices such as the Ethernet adapter may be captured and used by one computer over the other, so the solution to this would be to first pair it with one computer and then attach the second computer to the daisy chain.
In addition to which devices might be using the controller, the adapter may show reduced performance when connected to high-bandwidth devices such as RAID enclosures, which suggests that other Thunderbolt devices may show similar performance degradation when attached to high-throughput peripherals. Therefore, if your devices are not giving you the performance you desire, try rearranging them in the daisy chain, or using separate Thunderbolt connections. While many of Apple's systems only have one Thunderbolt connection, newer systems are ... [Read more]