Prontosw,

The standard suggestion is to make sure that everything is using the latest software: router, TSU9600, RF9400/9600.

One or my customers has had trouble similar to yours. I suspect that it is router related, he is using an Airport Extreme (an early draft-N version). After a Pronto upgrade there is grief from one 9600 or the other (does not seem to be the same unit each update), then things settle down after a few days. All the while he is tinkering with the router. Therefore, I don't know exactly what he has done with the router. Sometimes fixing the Pronto's IP addresses seems to work, other times DHCP is the magic bullet. Overall, fixed seems to be more reliable with the Airport Extreme. With other routers, in my experience, it does not seem to matter.