Dhcp ipv4 no reply

My wan is dhcp, but when i requested ip, the dhcp server did not reply. after restart network, i got the reply. why? how to solve it ? thanks

not always, just sometimes

maybe start by providing your configuration...

Please copy the output of the following commands and post it here using the "Preformatted text </> " button:
Remember to redact passwords, MAC addresses and any public IP addresses you may have:

cat /etc/config/network
cat /etc/config/wireless
cat /etc/config/dhcp
cat /etc/config/firewall

this is the discover message