以下是Ubuntu dhclient故障排查技巧：
ip addr show或ifconfig確認接口已啟用且配置正確。sudo systemctl restart networking或sudo systemctl restart NetworkManager。sudo dhclient -r釋放租約，再sudo dhclient重新獲取。journalctl -u dhclient或cat /var/log/syslog | grep dhclient排查錯誤。sudo ufw disable。/etc/netplan/*.yaml（Ubuntu 18.04+）或/etc/dhcp/dhclient.conf，確保DHCP配置無誤。/etc/sysctl.conf中添加net.ipv6.conf.all.disable_ipv6=1并執行sudo sysctl -p。若以上步驟無效，可能是硬件故障或需聯系網絡管理員進一步排查。
