I had difficulty getting my CS-WX set up out of box with error of no network connection too.
I plugged the CS-WX ethernet directly to my laptop ethernet plug. Configured my laptop ethernet's ip address to 169.254.1.111 (where 111 is random number different than the one generated and being used by CS for its ip address) This should put the CS and laptop on same LAN, and able to communicate.
Run Nas Nav . Hope it sees the CS-WX (if not, I don't know what else to suggest.)
Play around with Log on to CS-WX web ui, your shares etc.
Back to business, do the force firmware upgrade as instructed in the FAQ mentioned in earlier posts.
After firmware upgrade, (power off of course), plug CS-WX back into router, and hopefully i53 is now gone away, and you are up and running.