The sensor should repeat "find parent" until it gets a response. So there seems to be a problem with the sensor anyway. Has the Arduino been used for something else before? Sometimes clearing the eeprom helps. http://www.mysensors.org/build/debug#clearing-eeprom The radio channel can be changed in MyConfig.h https://github.com/mysensors/Arduino/blob/development/libraries/MySensors/MyConfig.h#L314 but it shouldn't be a problem unless your wifi is extremely busy.