solved solved solved
First of all, let's get some extra info: What is the OpenWrt device and what version of OpenWrt is on it?What kind of modem?
A few things:
- Are you sure you're connecting the WAN port on the OpenWrt device to the modem?
- If the above is yes, then I wonder if the ethernet port on your OpenWrt device is simply not recognizing the ethernet device on the modem. Does your OpenWrt device have ethernet lights on its WAN port?
- Cloning the other router's MAC address on to br-lan is not what you want to do - br-lan is the LAN ehternet port switch bridge.
You have to do lan-wan routing to be the first device connected to a modem. For IPv4 there is only one "public" IP address issued by the ISP, so you have to NAT and route all the devices into that one IP.
How is the ISP router WAN interface configured (DHCP, PPPoE, ...)? Is the OpenWrt device configured the same? Did you clone the MAC address from the ISP router to the LAN or the WAN interface on the OpenWrt router?
Can I suggest that deleting your question and not posting the answer is counter productive to the forum that you sought help from?
This is the OP's question, retrieved from the publicly-visible edit history, in case anyone else may benefit from it: