When you switch the channels, you also re-download with the correct channel selection I presume?
Come to think of it, assigning a static IP address in stand-alone will not work. Most stand-alone network devices calculate their own IP address based upon the mac address, apparently the same goes for the RFX9400.
i.e. once you switch to stand-alone the RFX9400 will calculate its own IP address.

Try using standalone mode and do not set the IP address in the configuration. Check the Channel used on your wireless network and try to separate both networks as much as possible: e.g. if your wifi has channel 6 use 1 or 3 on your RFX9400...