The unit sends a DHCP too fast for 8 of 9 managed hubs

To clarify: Do you mean that it sends the DHCPREQUEST too soon after link is brought up -- and thus the hub drops it? Or do you mean it times out too quickly for these hubs?

You seem to be saying the first of these, but I want to be clear.

Also, which hubs/switches had difficulty? It'll help us in testing stuff in future.

And, as for the log file, it's probably a difference between the debug and release builds. ISTR that the Rio Receiver Manager software isn't particularly loquacious in a release build, when compared to emplode (for the car player), for example.