I suggest it may help comprehension of how to solve your problem if you first adjust your mindset a bit:
There's no such thing as "Wi_Fi Signal" as if it's some ethereal energy field like The Force or Ley Lines generated by your "router" that you kind of "hook on" to like some strap hanging commuter.
Wi-Fi works like sound, only using radio waves instead of sound waves. Just as there is no "audio signal" (field) wherever you are reading this, there is no "Wi-Fi signal" (field.)
Wi-Fi is a two-way radio "conversation" between communicating peers, not a one-way radio "lecture" like television. I speak, you listen, you speak, I listen. Same for Wi-Fi.
In order to maintain a conversation, both parties need to be able to "hear" each other clearly. If they cannot, then you either need to make (both) parties shout louder, remove any physical obstructions between them, move closer together or some combination of the three.
Wi-Fi transmit power is limited by law and most kit is, and always has been, transmitting as loudly as permitted. There's no magic "uber-router" out there with "much better signal" than everyone else. Even if there were, that only "fixes" the problem one way (and actually creates other issues.) It does nothing for the client-->router transmissions.
Taking down the walls is probably inconvenient, so the only remaining option is to move the communicating peers closer together. Either you need to go sit nearer your router, or deploy additional Wi-Fi hotspots closer to where your client devices are.
99% of the time that means putting up additional Wi-Fi Access Points (AP's) closer to the target areas and creating a "cellular" coverage pattern of Wi-Fi HotSpots. On big sites, we put up hundreds.
The "trick" with a deployment of multiple hotspots is how you establish the "backhaul" link between the outpost AP's and the rest of the (wired) network. Proper wired ethernet is by far the best (fastest and most reliable) backhaul, but it's also possible to backhaul using things like HomePlugs and Wi-Fi itself (using things like "Repeaters" - sometimes given silly "marketing" names like "Extenders" and "mesh" nodes,) though HomePlug/Repeaters both have their own vices.
So a forklift router replacement might give you a few percent improvement, might be the same, might be worse and will need to be "compatible" with you ISP. You simply don't know until you try it - it's a gamble. For the same money, an additional Wi-Fi hotspot(s) gives you a guaranteed 100% coverage area improvement wherever you deploy it with the benefit that you don't have to do a thing to you existing "router" or "worry" that it's replacement is compatible with your ISP.
Wi-Fi is facilitated by AP's not "routers." This isn't just hair splitting over nomenclature, in the field of data networking an "AP" and a "router" are very different things; it just happens that the SOHO "get-you-on-the-Internet" omni-box contains both and a bunch of other stuff. To deploy more Wi-Fi hotspot, you "only" need more AP's, not more "routers." AP's get built into lots of "other" things e.g. Super/Virgin/BT "hubs" Homeplugs, even phones. What makes an AP and AP is the software it's running more so than the hardware - though the hardware does "matter."
As discussed, the hard part with multiple AP's is establishing the backhaul - we can get into the weeds of that if you select that option.