Unfortunately we can”t add more details that in an appear answer... there could be issues both with adapter or with some hang from the phone’s side.
Try to remove OBD WiFi connection point in phone’s settings. Reload phone, or turn off/on WiFi. Start car’s engine, unplug/plug back adapter, check that it is powered. Switch phone to flight mode. Check and turn off any proxy or other apps that could change IP addresses. Open WiFi settings and try to search and setup connection with OBD adapter. If this does not work, great chance that adapter is dead.
Thanks