Z-Com R1 Extender manual and set the IP Subnet Mask on both as

192.168.1.2 and set the IP Subnet Mask on both as 255.255.255.0

Warning:

Each IP address is unique within a LAN, otherwise IP collision may occur!

Open “Radio” in “Wireless” and you will find the default operating mode is Peer-to-Peer (CSMA). Select to use the Peer-to-Peer (CSMA) operating mode and keep the Channel/Frequency and Bandwidth on both R1 Extenders identical. Click “Apply” to save settings.

Chapter 4 Configuration Page 15