I have two devices which both run the latest stable release 18.06.5. Unfortunately, my Netgear EX6150v2 rage extender cant connect to internet. It is not about configuring as relaydaemon yet, I first want to make it connect to the internet in order to update LuCI with latest updates and download the necessary software.
I can connect to both of them with LuCI and SSH. I gave the first device (TP-Link router) 192.168.1.1 and the Netgear device the address 192.168.1.2 and told it to use 192.168.1.1 as gateway and checked Disable DHCP for this interface in Network > Interfaces > LAN > Edit. Although these steps are not unfamiliar to me, I checked the quick start troubleshooting guide
Network diagnostics shows me:
Ping: "ping: "bad address 'google.com'" but if I go for 22.214.171.124 or 192.168.1.1 everything is fine!
traceroute: "traceroute: bad address 'google.com'" plus same as above
NSlookup: ";; connection timed out; no servers could be reached" - doesnt matter if I search for 126.96.36.199 or google
Similar behaviour when I SSL into the box:
root@OpenWrt:~# opkg update
* opkg_download: Failed to download http://downloads.openwrt.org/releases/18.06.5/packages/arm_cortex-a7_neon-vfpv4/telephony/Packages.gz, wget returned 4.
* opkg_download: Check your network settings and connectivity.
Whatever you do, do not use opkg upgrade on any openwrt device unless a) you know what you are doing and upgrade only specific/known safe packages, or b) are willing to deal with the fact that you will almost certainly have problems that will require a reset to defaults situation.
I say this because you do not need to, and should never upgrade any of the core openwrt packages with this method (and you mentioned doing just this in your op). It will break things. Period.
Using opkg update followed by opkg install is, of course, totally fine to install additional packages.