@DKS736 

You would want the M9 being the main router.

Another setup can be using powerline adapters so you can have the TL-PA7010PKIT, one wired to the main or satellite Deco, and the other wired to the furthest Deco. 

modem > M9 > PA7010P ----electrical outlet----PA7010P > (any Deco model)

You can get a single Deco node such as an M5 rather than the P9.

@Tony I tried a set of PL7017's but can't get them to connect. Distance is approximately 200' of wire and through a sub panel.  Tried both legs. Units do work inside the house, although speed is not great (50 mbps) with both in the same room. Would a higher quality unit (AV2000) make a difference?

@DKS736 If you have coax in the outerbuiling, I would look at moca network adapters. It runs ethernet over coax.  

For the powerline devices, make sure they are plugged directly to the outlet. Any power protector/suppressor will block the signal.