I use a Yun with temperature probes storing values in a SD card. To monitor the datas, I ask it trought the WiFi AP with my PC or my mobile.
The problem is, in case of power down of Yun and the WiFI AP, the Yun starts more quickly as the AP Modem router. Without WiFi AP signal, it comes in the setup config, sendig the SSID "Arduino un-XXXXXXX" and I must reconfigure the WiFi link, not so easy in the cave of the house.
Note if the WiFi AP is powered off, then on, the Yun reconnect correctly.
I tried to set a static address, by the LuCI Web panel, but without better results. Any idea?