@Alarm_Guy1 

If you are looking at 8+ of the powerline adaptors, then honestly my advice would be to move to a Mesh solution.  From experience having that many powerline adaptors running will drag performance to a halt, it really does degrade after around 4 adaptors..  The main issue is the flooding of the powerlines themselves, its not designed for that many plugs to be in operation.

Depending on your budget, the Deco Mesh devices may be a good idea for you.   Cheap 3 pack of the M4s would get you started and covers a good range, ive seen houses of 5000 sqft covered with just 4 Deco nodes.

The advantage of these, works as one network and can be cabled in if you want that faster performance.. if not will work wirelessly.   If you have a black spot, just buy one more and add it on.  You can mix and match these as you need, for example X20 mid range in the main busy area... M4 cheaper model in the garage  etc etc..

M4 and S7 is your base and base + models, cheap and decent enough for home use

X20 would be the mid range, faster and bit more powerful at a higher price

X60 or higher are the premium stuff, expensive and fully featured.  

They come in packs of 1 2 or 3..   3 would cover most houses and if you do find a dead spot, add another single node (doesnt have to be the same model).  Try to keep the best models at the busy / main areas.

Hope that helps!

  @Philbert 

Thankyou.

they currently have Linksys Velop that seems a bit flakey at best with 5 or 6 nodes.

My concern is spending the money, and it not performing as expected

it needs to just work, there is no way to cable as it has been completely refurbed before they purchased it.

We have the 4 TP-link Extenders that are picking up 4 cameras, we are not currently using the Wifi on the Extenders.

The Velop system is just a nightmare it never reconnects and takes an age to setup again, it is horrible

Plus the job is over 1 hour away :-(

  @Alarm_Guy1 

That does sound like a bit of a nightmare for you!   Ideally a cable solution would be the best for you, even partially to allow some backbone away from the WiFi, any chance of cabling in the attaic and mounting a few APs on the ceiling below?    Let the signal come from above down, something like an EAP 245 might be an option as these are more directional.

Outside that, mesh is handy but as you say not always the perfect answer.  Personally i have not used the Linksys myself so cant comment on that one.

Is there any coax in the house?   Would a moxa network be an option if there is?   even partially would help you massively.