@Chenxintao Hi friend,
Sorry for the delay in response.
The devices connects to wifi, but no ping to internet or gateway.
If we connect PC directly to ONT, the devices works without any issues.
As we checked, the problem is mainly with device roaming.
If we connect a device to wifi through an access switch connected through swtich,
and roam to a place where access point is connected through ONT, the issue shows up