Sonos, TP LInk and mesh - what is it please?

[#1]

My flat is quite small but for some reason the Wifi won't extend very well and I need a TP link which is working fine. However, my Sonos speakers are on two different Wifis which causes some issues.

One speaker is in the bedroom where the router is, and is on the main Wifi (wireless).

The others in the sitting room and kitchen are on the TP link network (wireless). The system sometimes goes awry. 

It's been recommended I use a mesh router. I don't have a clue what mesh is or how it works, but I looked on this forum and saw that someone else had used mesh effectively with Plusnet. I would be very grateful if someone could explain to me what this is, and the benefits if any it would have for me. Thank you!

[#2]

Hi, can you connect the speaker in the bedroom to the router ? That should enable the Sonos mesh

[#3]

Thanks for your reply. Should that be the main rotor or the TP Link? I used to have it attached to the Plusnet router but that made the probllem worse.

[#4]

I've a Sonos boost which creates it's own network but it looks like its being phased out.  Sonos are now saying connect one speaker to your router so the boost is no longer required. More details which you should helpful  :

Sonos end of boost check the wired setup...

[#5]

Thanks - I will try plugging it into the TP Link router.