no ip address

The extender connecte with for my MacBook for several weeks, but today I get the message "No IP address" for the extender and therefore no connection. My regular wifi is working fine - both 2.4 and 5 but I need the extender for some areas in the house. Where can I find this address? If I do need to use another IP address, for the extender will it interfere with my base wifi connection ?