South African homes are built from brick and concrete, and every wall costs you signal. A router sitting in a corner study behind two walls and a geyser cupboard will never cover the far bedroom, no matter which package you pay for.
Move the router first. Central, off the floor, out of a cabinet, away from the microwave and the fish tank. This one change solves a surprising number of complaints and costs nothing.
If the house is long or double storey, a single router is the wrong tool. A mesh system with two or three nodes hands your phone between units as you walk, so you keep one network name and one password. It beats a cheap range extender, which halves your throughput and creates a second network you have to switch to manually.
For a home office or a gaming setup, run a cable. A twenty metre CAT6 run to a desk gives you stable low latency that no wireless link can match. We install trunking so the cable does not look like an afterthought.
Finally, check how many devices are actually connected. Twenty five devices on an entry level router will choke it. Upgrading the router is often cheaper than upgrading the line.