The placement of your router, the size of your house and the materials of which your house is built of all have a significant impact on your wireless signal strength.
Place your router as high up as possible, freestanding and ideally in an area close to the product(s).
Hard surfaces like concrete walls, glass and metal can greatly decrease the signal strength.
You can also view ‘Update your router software’ if you want to know more about how to optimise and maintain your Wi-Fi network.