Br-lan client can not connect problem

There are 2 clients connect to AP and play youtube video.
one client connect to 2.4Ghz, another connect to 5Ghz.
After 15 hours, both clients wifi is connected.
But one client connect to 2.4Ghz show no Internet. This client(ip is can not ping to gateway ip(
Another client is OK.

How come this client still got the assigned ip(, but it can not ping to gateway ip(,
also can not connect to Internet.
is there any suggestion?