wifi extender compatible with a XAV5101

What are you trying to achieve?

The EX2700 looks like a Powerline device, but it isn't. It "listens" to the wifi from a router or something else and passes it on to wifi clients, or things you plug into the LAN port.

The EX2700 is a wifi repeater: it will not take the LAN from the Powerline Ethernet and pass it on as wifi.

It explains this on page 40 of the manual which is somewhere at the end of this link:

>>> EX2700 | Product | Support | NETGEAR <<<

If you want to take the LAN from the XAV5101 and use it as a source for a wifi extender, then you need a device that can work as a wifi access point.

Just check Netgear's range of extenders for one that also supports access point mode.

WiFi Range Extenders: Boost Your WiFi Range | NETGEAR

To pick just one at random, the EX6100 says that it will work as an access point. So you could plug it into the XAV5101 to get wifi out of the EX6100.

You can also buy Powerline plugs that double as access points. They will work with your existing Powerline Ethernet. But you'd have to buy a bundled pair and add them to your existing Powerline network.

XWNB5201 | Powerline | Networking | Home | NETGEAR

Like I said, tell us what you want to do and you might get clearer advice.