@Bearcatboy You should do more researches about the powerline option but per many reviews it does not perform well compared to other types. It's best to extend Ethernet to garage (can you look at buried conduit with proper insulation), or by any change your garage has coax wiring? If yes, get a pair of Moca adapter and extend Ethernet to your garage with an x50 Outdoor node. I did that and the Outdoor node covers my whole back yard as well will almost 500mbps up/down.

  @Bearcatboy 

So , the first two replies advise against using the “Powerline” feature.  It sounds like good advice.  There is one way that would make the installation of Ethernet Cable fairly easy for me but I believe that it is one of the big No-No’s for running Ethernet Cable.  That would be to feed the CAT5/6 through the same conduit that carries the AC wiring to the garage from the breaker panel in the basement of the house.  If anyone knows of a way to do that effectively (and do no harm), I think PoE would be fairly easy to pull off.  Running new cable underground, by it self, or in its’ own conduit, is of course possible - it’s just a lot of work and expense that I was hoping to avoid.  

Thanks for helping me to begin to sort out the TP-Link product line.   It's too bad their marketing people can't do that better.  

  @Bearcatboy Powerline adapters do not need to be on the same circuit, they need to be on the same breaker panel or on the same meter.
Otherwise it would never be possible to use Powerline.

What is the distance between your garage and the house?

  @yves_b 

I agree that the Powerline feature would be pretty useless if devises had to be on the same circuit (breaker).  I think it is possible that they have to be on the same phase of the circuit panel or something needs to be added between phases if they are not.   Normally, the only thing in common between phases in the panel are Neutral and Earth Ground.  
 

That said, I do value the experience that users have had with that feature.  Are there any success stories out there?

And one more complication, apparently the Deco X50 - Outdoor does not have the Powerline feature so I would have to use an Adapter.  That would be an additional cost and possibly additional "issues".

Concerning distance:

- house (panel) to garage - about 30 ft.

- across garage to Mesh - about 30 ft.

- across house - Mesh to panel - about 20 ft.

- extra because wiring ain't straight - about 10 ft.

- TOTAL WIRE - about 90 - 100 ft?

  @Riley_S 

WOW! The info you are feeding me is so valuable.  Thank you.  Things like incompatibilities between system components - in today’s world those are often painfully learned through the school of hard knocks.  And breakers that have noise filtering built in - I was not aware of that feature and I do see where that could sure mess with data transmission.  By the way, the garage is a circuit by itself and it might not be that difficult to move the wiring of the Main Deco AC outlet to that circuit - I will have to trace some wiring to check.  I don’t think it would overload the garage circuit.

  @Bearcatboy 

Indeed, you would need to have two Powerline Deco, one in the house, one in the garage.
Be aware that P9 and PX50 are not compatible from a Powerline perspective, they will not communicate via the power lines.

If the indoor Deco in the garage does not provide sufficient outdoor coverage, you would indeed need an additional appliance for that.

I am not convinced that a mesh is the most cost effective solution in your case. Do you actually require transparent roaming, which is the strong point of a mesh?

I suggest considering a good wifi appliance for your house, two affordable powerline appliances and an outdoor wifi access point.

  @yves_b 

OK, so here’s the direction I am heading and some questions about implementing my plan:

First, averaging all the connection discussion together, I think I need to bite-the-bullet and run Ethernet cable to the garage and take advantage of POE and uncompromising data transfer to and from the Outside Node that the cable offers.  The only model that meets this solution is Deco X50 - Outdoor.  Current Amazon price $130.

For my Indoor, main Deco, I think either Deco X50-POE-Indoor (2 gigabit POE Ports) - $110

or

Deco X55 (3 gigabit NON-POE Ports) - $90.  The 3 ports model has some attraction for me since my system has 1 device (located indoors) that requires a direct Ethernet port connection.

Now for the my next area of ignorance:

How do I inject the POE power into the above plan?  Again, (especially since the above is going to cost me more than hoped), I would like to do this for a reasonable price.

Thanks for all your help.

  @Bearcatboy 

II do not see any reason to use POE.

POE is an alternative to AC Power for powering an appliance.

POE is used usually when there is no convenient AC power source available for an appliance.

In that case, the appliance can be powered via the Ethernet cable.

Something (usually a POE capable Ethernet switch) needs to inject power in the Ethernet cable, the Deco can be powered via POE, but they do not inject power on the Ethernet cable.

As far as I know, all POE Deco can also be powered from an AC power source.