Good Router / Switch as a Bridging Router / Switch (UK!)

[Sir Topham Hatt]

Can anyone recommend what I should be looking at for a bridging router / switch (I think I got told off for calling it a router)?

I have:

Modem > TP Link M4 in router mode > (wireless) > TP Link M4 > PC (wired connection).

Firstly, my PC has wifi in the motherboard so I might get rid of the network cable connecitng it to the 2nd M4 tower - it probably won't make a difference though, would it?  This is relevent later on.

Secondly, I was thinking about buying a router to put in the middle of both M4 towers as the 2nd one has a "weak" signal (first M4 tower is 6m away (in living room), then a little porch area, then another 5m to the 2nd tower).  Half the 6m in the living room has a weird roof, which carries on to the rest of the house where the 2nd M4 tower is.  The roof is very good at blocking signals.

What router could I use and would it strengthen the link between the two M4 towers?

Thirdly, perhaps I could move the 2nd TP M4 tower to the porch area and then make the PC use wireless, thus not having to pay for anything.  This could work but I'm not sure how well and not sure I want to disturb my current set up too much to try (although it wouldn't be that hard I suppose).

Any advice?
I'll try and get a photo of the layout tomorrow, which will explain everything a bit better.

[Sir Topham Hatt]

Photo

 

Yellow spots = TP-Link M4 nodes
Red spot = ISP router (in modem mode)

Light green "Hall" was where I was thinking of siting an access point but to save a lot of messing about, the blue spot would be worth a shot first.

Between the windows in the Lounge there's an active real fireplace, so I can't run any ethernet there.  I don't really want to be running cables outside of the house, although there is a cable that comes into the house just behind the yellow and red spots but then you bump into the Utility room, which isn't made of normal brick and would be difficult to route any cables into (there's some plastic cladding on the outside of it - drilling through would be a mess.  Beyond that is a (light blue room) bathroom so it's easier to think about whether I can transmit inside rather than running cables outside.