Six Things That Block Your Wi-Fi

1. Your Neighbors' Wi-Fi Networks

2. Household Electronics  ( microwave ovens, cordless phones )

3. Bluetooth Devices

4. Humans

You might recall from science class that the human body is mostly water, anywhere from 45 percent to 75 percent depending on your age and fitness level. Water can hamper Wi-Fi speeds, too.
"For example, say your room is very crowded and you're having a party. That can actually dampen your Wi-Fi signal--but that's an extreme case".

5. Security Settings of router

6. Old Firmware of router