Brett,
The RFX9600 does not have WI-Fi capabilities and MUST be connected to the wired network. Some have used static IPs for extender and got this working. Quite honestly, I only use static IPs for extenders (configured in Extender Web interface). This ensures that my network topology remains consistent.
Being new to this forum, you will benefit by learning to search. A quick search for last 1 year in this forum only for +Extender +WEP yielded the following:
[Link: remotecentral.com]There are suggestions in several of the topics resulting from the above search.