[Wireless Router] Is it possible for the router to operate exclusively for an intranet without a WAN connection?
Yes, it's possible for router to do the intranet work without wan source.
No need to set the router with WAN first if user only need to use the DHCP Server function of router to assign IP for the clients and work in the Intranet.
How to get the (Utility / Firmware)?
You can download the latest drivers, software, firmware and user manuals in the ASUS Download Center.
If you need more information about the ASUS Download Center, please refer this link.