Sorry! I did not explain myself well.
I changed the prefix with the command “redBear Duo : dfu-util -d 2b04:d058 -a 1 -s 1826 -D ssid_prefix”, it worked for me.
There is around 20 devices deployed around mexico, 3 of them presented the same issue over the same conditions.
On the 3 cases, there was a power cut. Once the device powered on again, the SSID prefix resets to DUO_XXX.
This causes that our app does not works for set wifi credential because it cant find the device net.