Router Placement
Try placing your wireless router away from other Wi-Fi network or transmitting devices such as Bluetooth, refrigerators, cordless phones, microwave ovens and baby monitors. This can cause a significant decrease in speed, or the total blocking of the Wi-Fi signal when these devices are used near the router or other Wi-Fi connected devices.
Reboot router
Rebooting (turning off and then back on) your router solves most Wi-Fi issues. Upon rebooting newer model routers generally select the least crowded frequencies.
Dual-Band
If you have a dual-band router like the Fios Quantum Gateway, try enabling both 2.4GHz and 5GHz. If you experience interference, switch to the 5 GHz channel and get closer to the router (or place the router to where you use Wi-Fi connections most often). The 5 GHz channel generally provides the highest possible throughput, but will have shorter range than the 2.4 GHz channel.
Note: When testing speed wirelessly, it is best to test away from other devices or turn off other devices.