I tried a few solutions I found here and on other sites. Not sure exactly which step fixed it, but I'm up and running now with no self-assigned IP address issues. Note, my setup also has a Powerline ethernet adapter that's plugged into my wall outlet and acts as an ethernet port. Here is what I did:
Your new Ethernet service should be green and have it's own IP address.
Tried what you advised. The 154 post did not work for me, since it could find flush command.
I've tried a good number of the other avenues and had come up empty until I did the following:
1. Network, uncheck passive box under proxies for ethernet.
2. Plug in ethernet. Reboot router with ethernet still plugged in, and then got a green ethernet that i'm using right now to post this.
I tried unplugging and plugging back in and restarting router with it unplugged, but it then worked when plugged in a rebooted router.
Just saying that something actually ended up working.