Expand Wi-Fi coverage in my home
I am trying to upgrade the Wi-Fi coverage in my parent's home. I haven't done networking before and don't know a lot of the technicalities of networking in general. Hence, I wanted some advice.
Please check the layout of my home shared below.
The walls are 5 inches thick.
Router A has the better internet speed plan and the home PC is also there connected via Ethernet. Router B is just for the smart TV that's in that room, also connected via Ethernet. Router B is on a different ISP, and the router is also provided by the ISP. I don't have any intentions to change it at the moment.
I wanted to expand the coverage of Router A. Currently, the green area is the one where the signal is the strongest. The red area is where the Wi-Fi starts losing bars and the connectivity surprisingly suffers a lot. For example, if I was trying to connect my TV which is right where Router B is, the TV would lose connection to Router A pretty often. Same with our smartphones.
Router A is an old TP-Link WR841N 300mbps model.
Will investing in a better newer router model with more antennas solve the issue? Or do I require Wi-Fi range extender in each of the other rooms?
Again, I am not quite knowledgeable about networking yet, I am still learning. So, any kind of advice is greatly appreciated. If any other info is required, do let me know.
Here is the layout of the home: