Mikepsych283 gave some good advice. Echo, Hue, Wemo, and other recent Wifi devices usually operate on 802.11n (aka Wireless N).
Wireless N is backwards compatible with Wireless B and Wireless G. Thus using an old router may work better, but that all depends on what kind of equipment you have.
The newest routers operate on 802.11ac (aka Wireless AC). If you have one of these new routers, make sure that Wireless N is turned on. Wireless AC is not backwards compatible with N, B, or G. Also, these new routers operate on two frequencies, 2.4GHz and 5.8GHz which can be turned on or off independently. I believe Echo, Hue, Wemo only can use the 2.4GHz frequency. So make sure that is turned on in your router.
With this information, you should check your router and make sure that the 2.4GHz frequency is turned on and using the Wireless N protocol.