Some APs will do auto selection of channel to use. Some give you the option to turn that off. If an AP decides to change channels, the clients need to keep up. The client then need to figure out what to do. If both sides are trying to be smart about what they do, but don’t communicate it well, it will lead to miscommunication, which seems like what you are seeing. The problem appears to be happening because the AP that is farthest away sometimes becomes the “best” one in Iotawatt’s view. Try turning it off and see if things improve.