Older Airport Express, Airport Utility
I have an older (about 2005-2006 vintage) Airport Express that is used as a satellite base station (network extender?). This old Express works flawlessly to extend a household / home office network and to allow for a workgroup printer to be connected in the office.
The "mothership" is currently an aging (2004 vintage) round white Airport Extreme, which has been having problems. We just bought a refurbished late-model Airport Express from Apple direct to replace the old Extreme as the "mothership". (The current "mothership" is connected via Ethernet cable to a DSL modem, so it is our network hub and our gateway to the internet.)
I'm thinking seriously about reconstituting the LAN situation; shut everything down, disconnect the old Extreme, and plug-in the new Express and build a new LAN with new network ID, password, etc. to save time and headache. No decision has been made yet. Nothing has been done. Problem: the "old" Airport Express is vital to what we do. We need to incorporate the "old" Express into the "new" network.
I tried launching the Airport Admin Utility on one of our newer (2012/2013) computers today, and the Utility cannot access either the "old" Extreme or the "old" Express. The Utility says these devices are not supported by this version of the Utility software. If I do go ahead and rebuild the LAN with a new "mothership" ("new" Express), network ID and password, how do I program the "old" Express to join the "new" LAN?
iMac, OS X Mavericks (10.9.5), late-2012 Core i5, 8GB RAM, 1 TB HD