Mesh home network using available devices

Hello folks.
my parents have a big house, and we have problems with wifi signal.


At 1st Floor i have my cable router with 200mbps internet connection, and a tplink WDR 3600 router (1)
On the ground floor, i have a WDR 3600 Router (2) and a Tp-link WPA8630PKIT powerline with ac and 1200mbpts.
on the Garage i have a samknows sk-wb8 with lede firmware.

From the 1st floor to all the devices i have CAT6 cable at 1000mbpts, except to the garage... were i use powerline to get the network there.
Problems here are that:

  • Powerline sometimes fails, and IPcameras connected to garage switch sometimes fail to record on the NVR at 1st Floor, disconnect and reconnect starts to work again.
  • I have multiple SSIDs around home, and they dont make exchange between them to the best signal.

what im thinking...
Keeping the WDR3600 routers connected with cable but working as mesh network, with same ssid, the sk-wb8, meshing with the wdr3600 signal, and putting the plc adapters out.

Getting fast internet access with roaming between all devices.
wifi signal is only for tablets, laptops and phones, but i get some massive use from tvheadend server on the network, to watch tv with kodi on the tablets or Wifi connected tv

What is the best diagram and configurations i should use? both 3 routers are openwrt capable and with 128mb ram...

First I'd log into the garage router and run some scans to see what the signal levels are from your AP's in the house, and of course also check garage signal strength at the house routers. That would establish the feasibility of wifi links using the existing equipment in its existing locations.

You don't need a mesh here, a basic WDS from the best router in the house to the garage would be fine. The powerline link can be left in place but be sure to enable STP on the LAN network bridges so that a loop won't crash your network.

Mesh in the OpenWrt world is only a method to bridge backhaul links on the LAN side. The commercial "mesh" systems also claim to have enhanced roaming of clients. This is an entirely different area of software development. There is not much available for that open-source.

IEEE 802.11k/v/r are available on OpenWrt (reducing handover time and giving the clients the data necessary to improve roaming), the only thing that's missing would be AP side bandsteering and kicking off clients based on the APs estimates, leaving the roaming decisions to the client (which don't always do a good job about it).