We like to use Andriod phones as SIP clients but Phones disconnect from network randomly. They may not disconnect for 2 days or may disconnect in 2 hours. If two phones sitting next to each other, one stays connected, another disconnects. To bring them back, we need to move out of coverage area and come back or turn off the wi-fi and turn on again. We have cisco WLC and cisco APs for wifi network.
I used an APP called Wi-FI fixer, and attached are logs