I am also having problems with the images supplied by dfrobot.  My board with a recently purchased CM module works fine if i load raspberry pi OS on it.  it boots and both network interfaces along with the wifi all seem to work fine.  

when i try the dfrobot openwrt images, it looks as if it boots, and eth0 works  – i get both a yellow link light and green traffic lights – but eth1 does not show any lights.  that's what i need to connect to to get to the admin panel or ssh.   when i plug eth0 into my network, it looks like something is going on, but i can't find its ip address so not sure if it is using dhcp or some hard coded ip address.  my guess is that the driver for the eth1 interface was not loaded.

i will try the official openwrt images next to see…