If you cannot connect the camera to your WiFi router, or you constantly have lost or slow connection to the camera feed, consider moving your router closer to the camera. You may also use a WiFi extender to add it between the camera and router to bridge the connection. If you use an extender, remember to connect your camera to the extender’s network (instead of the router's).
If the connection to the router is good but you still get the slow connection, consider upgrading your Internet plan with your ISP. Generally, 3Mbps and more of download and upload speed is needed for 3MP IP Camera.
If your phone can stream fine using WiFi but you experience slow connection using cellular data or 4G, contact your phone manufacturer or phone carrier to see your option to upgrade your cellular plan/ speed.