Are these straight forward to install?
Yes. Instructions are good, take a look on the TP-Link web site for example "how to" videos, but written install instruction can be downloaded before you buy. You have to setup the first Deco with the hub in normal router mode. Write down IDs and passwords! When the first Deco is successfully setup, you need to put the hub in modem mode, when it comes back on line with a magenta LED, it will lock to the first ethernet connected device it finds, so make sure only the Deco is connected (if need be a further restart will be required to achieve that. From there on you setup the subsequent Decos. All setup is done via the Deco app, which is easy to use.
My current router is in the hallway on a shelf about 6 ft in the air .
You can either place the primary Deco next to it, or somewhere else, connected by an ethernet cable. The supplied ones aren't terribly long, but if you need to buy a longer Cat 6 or 7 cable they're cheap as chips.
We have a single story extension behind the kitchen which leads to garden . I have a power point on the landing .
Once configured, place the secondary Decos wherever you want and move if they aren't quite doing what you want. They only need a power supply, they don't use the mains for communication. Be aware that performance will still drop off if the signal has to reach through solid walls. Worst case you can connect a secondary Deco to the primary by long ethernet cable, which can solve solid wall problems, but requires possibly inconvenient cable runs. I haven't found that necessary, but mine's a modern house with partition or lightweight block internal walls. Garden coverage will vary depending on how well the signal spreads through windows and doors. I was using my Chromebook at the end of my garden yesterday, about 40 feet from the house, and still getting 160 Mbps, so good speeds are possible outside if circumstances are favourable, although I admit that was with all the windows open. If you want to you can add further Deco units later. If garden coverage is important try having a Deco on a windowsill.
I have 3 cables in the router at moment which go to extension room x2 eg sky multiscreen box + smart TV and another linking the main sky q TV .
Then you'll need a fifteen pound "unmanaged gigabit ethernet switch" which to ordinary folks can be considered an ethernet port replicator, and plugs into the spare port on the primary Deco. I'm using a switch next to my Deco to attach a couple of devices that need a wired connection. That switch can be placed where it is most convenient, either next to the primary Deco, or just one long cable and put the switch next to the devices (it will come with a small PSU). In theory you can even use a switch to connect wired devices to a secondary Deco that itself is wireless, but I've not done that myself. You could keep the ports on the Hub 3 live by using the hub in router mode, and setting the Decos as access point mode, but then you're relying on the hub's pound shop router that struggles with a lot of connected devices. And due to a bug in the hub's firmware, although that configuration would be best with the hub's wifi turned off, it has a habit of ignoring the setting and turning the hub wifi back on, creating a competing wifi signal. I'd recommend modem mode to get the best from any mesh system.
Is it just a matter of a cable from router to primary and then install secondary in desired spots .
In concept yes. It will all seem very complicated when you're surrounded by unboxed Decos, bits of cable, and following the instructions, waiting ten minutes for a rebooted hub to come back on line, but stick with it. Once set up it minds its own business and performs flawlessly based on my experience. Don't forget to reboot the hub once a month - because the wifi works well you won't normally need to touch the hub, but it (the hub) does benefit from an occasional power off reboot to clear everything down and reload.
If this is all too complicated then the BT Whole Home Disks could be a pricier and fractionally easier option. They don't have a router built in, so you're still reliant on the hub's crummy routing functions (and suffering any hub firmware bugs), they still need configuring, but you don't need to put the hub in modem mode or buy a switch. I'd recommend the Deco over the BT Disks, but family who use the BT Disks (albeit with a BT hub that's better than the VM hubs) are very pleased with the performance.
