Solution #5: Measure your signal’s strength
There are loads of apps out there for your smartphone that act as a gauge of the quality of the WiFi signal wherever you’re standing. They work even better if your phone is in a rubber case since your body itself will absorb and boost the signal. The less you directly touch the device the more accurate the results will be.
Once you get the results throughout the house, you can construct a “connectivity map” that should help you determine the best place for your router. Bear in mind that if all your devices connect wirelessly it doesn’t matter where the modem is plugged in. You can relocate your cable or DSL modem to any room that has a cable connection, connect your router, and position it optimally.