I was having similar issue, then I tried to use omega as a router from below link:
https://docs.onion.io/omega2-docs/omega-router.html
It is now working fine for me, and ethernet is getting IP by dhcp.
But I also need a static ip on ethernet, so if in any case, dhcp is not working, it should be having the static ip.
I tried to create one more connection name as 'eth1' with interface as 'wan' as below:
config interface 'wan'
option ifname 'eth1'
option proto 'static'
option ipaddr '192.168.0.233'
option netmask '255.255.255.0'
option ip6assign '60'
But it is not working and one more interface 'eth1' is not being created. I tried with using interface as 'lan', it is also not working. Can anybody tell me how it can be done.
Again, my requirement is to have a static ip on ethernet, in case dhcp is not working.