Compatibility
There are wireless range extending devices that conform to all 802.11 protocols. 802.11 compliant devices are backwards compatible. 802.11n is the most recent and third-generation Wi-Fi standard for wireless home networking. 802.11n equipment is backward compatible with 802.11g or 802.11b gear.
An older range extender will not be able to repeat the signal of a newer generation router. Security encryption compatibility also matters and must be at the same level of compatibility for the signal to be extended. For example an older range extender which supports WEP and WPA will not be able to boost a WPA2 signal from a router.
Read more about this topic: Wireless Repeater