Make sure your router is out in the open, not behind anything, not under anything. Also, anything between the camera and the router, reduces wifi signal and speed.
It's best to have the router raised as high as you can, (It reduces the amount of furniture between it and the devices talking to it), and remember if the device is OUTSIDE the home, the signal may have to go through brick or cinder block wall, and the density of the outside wall can reduce the signal dramatically.
Let me know if this helps, if not I can provide more targeted information that may help.