Poor coverage in large homes is almost always a design problem. Reinforced concrete, steel framing and double-glazing absorb 5GHz and 6GHz signals, and a single router - however powerful - can't push through them.
The fix is access-point placement with wired backhaul: multiple APs placed so coverage overlaps, each with its own cable back to the switch. Channel planning and VLAN segmentation keep the network clean and fast.
Start with a predictive heat-map survey. It maps signal against your actual floor plan and construction, so APs go where they're needed - not where a router box suggests.
