Client connected to AP but no internet

Hi,
I have an issue in a ruijie network. I have 4 switches . 1 switch is connected to ISP router and other 3 are connected to that switch.
In one of those switches, APs are connected and its showing in the dashboard also.
Also Clients can connect to broadcasted SSID. but showing as "connected no internet" .
Tried rebooting the switch, internet connection was up for 20 minutes then it went as previous.
What could be the reason for this behaviour?

Hi
I'm sorry that we can't provide a specific solution for you based on current information
Can you help to check the follows aspects:
1. Make sure that all devices can get internet. You could ping 8.8.8.8, google.com on devices to test
2. Which device is the dhcp server? If it is the first switch, please make sure that the other switches have allow this vlan, and AP should have this vlan too.
3. Can terminals get ip address? If yes, please ping 8.8.8.8, google.com from the termial. If it does not work, please try to ping the gateway and traceroute 8.8.8.8 and google.com. If you can not get the ip address, please check the dhcp settings first on switch, then double confirm the step 2. If the second point is correct, you need to capture packets on the first switch and let me check for you.
In addition, please share the topology with me so I can further check for you.