What if a UTT Business Router Cannot Connect to the Network in the DHCP Mode

A UTT business router is connected to the ISP modem in DHCP mode, but cannot access the Internet, please use the following instructions to solve the problem.
1. a UTT Business Router (hereinafter shorted as “the Router"), such as UTT router N518W, AC750W, AC750GW, AC1220GW, ER518, ER840G and ER4240G. Firmware Version: 3.0.0 or above
2. a PC/laptop connected to the Router wirelessly or through an Ethernet cable
1. Connect the PC/laptop directly to the modem and see if it can access the Internet. If not, please contact Internet Service Provider for assistance.
2. If the PC/laptop can access the Internet, please disconnect it, then connect the Router directly to the modem, and connect the PC/laptop to the Router.
3. Run cmd, enter ipconfig/all in the Command Prompt window, then press Enter. Find the Physical Address and copy it.
4. Launch an Internet browser on the PC/laptop and type into the address bar. Enter the Router username and password when prompted (default username: admin, default password: admin).
5. Find Network > WAN and click WAN1. Paste the Physical Address to the MAC Address field then click Save. Reboot the Router and try to connect to the Internet again.
It is recommended to disable DNS Proxy in Network > DHCP Server.