A stronger router may not fix the route
Garden offices, extensions and thick-wall homes can make Wi-Fi weak even when the router itself is good. Before buying, map the route between the broadband entry point and the room that fails.
Check distance and obstacles
Walls, insulation, foil-backed boards, floors and appliances can reduce signal. Write down what the signal must pass through before choosing router, extender, mesh or cable options.
Check where devices can actually sit
A mesh node only helps if it can sit between the router and the weak area with reliable power and enough signal to repeat. If it sits in the dead zone, it repeats the problem.
Check wired options
Ethernet, outdoor-rated cable routes or properly planned access points may be better than another wireless box. For rented homes, check no-drill options and landlord restrictions first.
Use UK Shortlists next
Use the garden-office Wi-Fi shortlist after mapping your layout. It should be a fit decision, not a router-spec race.