My company's owner just built a giant house with ICF walls which block RF. Therefore we are trying to build him a "mesh" type wifi network with an Airport Extreme controlling 4 Airport Express units placed throughout his house. At first we had it working with 2 Express units which were plugged directly into the Airport Extreme, but since adding 2 more Express units we have not enough ports on the Extreme so have to plug them into a netgear switch which is then plugged into the Extreme, and now none of the Express units are getting DHCP from the Extreme. They all show up with an orange light in the management/config utility and each show a 169. self-assigned IP. Is it for some reason required to plug the Express Units directly into the Extreme? Our local apple dealer said the Express units could go through a switch if the Extreme was also plugged into the switch but this does not seem to be working for us. I am network admin for the owner's company and config cisco ASAs, wlan controllers, windows servers, VPNs, firewalls, etc., but this is my first time attempting Apple Airport configuration and I am shocked it did not "just work" like all other Apple stuff I have touched in the past.