When µFR Nano Online works in a 2.4GHz Low Energy HID mode and is paired with the host device (PC, phone), its Wi-Fi access point is turned off to save power.
To access the device frontend configuration panel, you need to disable (unpair) the 2.4GHz Low Energy connection on the host device first. After that, the access point with the WiFi SSID named as the serial number of the device (i.e. ON1XXXXX) will be turned on.
Finally, connect to this Wi-Fi access point and access the configuration panel by typing the IP address 192.168.4.1 into your browser.
Alternatively, you can reset the device to Wi-Fi Slave mode by resetting the device to factory settings using the uFR Online Flasher tool.