Here is my current setup - Scenario 1

House size: 650 square meters

NBN Modem: ZTE Modem H268A (turn off wifi signal)

Wifi Router (main): TP-Link Archer AC3150 with Powerline TL-PA902OP Kit connecting to one end (downstairs one end side of the house)

Wifi Range extender:TPLink RE350 AC1200: it is use to expand the range upstairs (one side of the house upstairs)

Wifi Access Point: TPLink Archer D7 connect with Powerline TL-PA902OP Kit on the other end. This is increase the signal of the other end of the house upstairs

Spare equipments: Optus Netgear cable modem CG3000-2STAUS and Linksys Wireless N-300 router and Netcomm Wireless N ADSL modem router. 1 spare TPlink 500 powerline adapter

Q1. Is it a better way to increase the wireless wifi signal across the rooms upstairs (both side of the house)?

I tried to setup the following scenario before:

Scenario 2:

NBN Modem: ZTE Modem H268A (turn off wifi signal)

Wifi Router (main): TP-Link Archer AC3150

Wifi Range extender:TPLink RE350 AC1200

This will expand the range upstairs on one side of the house

Scenario 3:

NBN Modem: ZTE Modem H268A (turn off wifi signal)

Wifi Router (main): TP-Link Archer AC3150

WDS Wireless briging: TPLink Archer D7 as wireless bridge talking to the TP-Link Archer router

The result is not as good as scenrio 1 & 2 and if i used the range extender to the router, it makes the wifi signal even worse.

Q2. Should I replace the whole scenario with any mesh system? If so, should I wait until ax mesh system comes later?

I hope TP-Link will have firmwares to upgrade all these products into one mesh and my next AX routers (intend to get a very mesh ax system - 3 piece ones covering approx 650 square meters for 4k video use) can work together with my old equipments.