Ex6100 not connecting

What modem are you running?

If you're running just a modem, you need modem-->router-->extender. 

if you're running a modem/router combo, then it comes down to more questions about what is failing exactly. 

So again, what model device specifically are you trying to connect to? 

And what firmware is on your extender?

Here's the support page for the EX6100 that includes the manual (useful for questions), install guide, and firmware. 

https://www.netgear.com/support/product/EX6100.aspx

A simple guide

https://kb.netgear.com/24432/How-do-I-install-my-NETGEAR-EX6100-extender