No matter, I thought, I'm sure the two will be pretty similar with this stuff and it seems I was right. So I was able to browse to the Omega after connecting to it's AP and I tried to setup the wifi connection but this failed even after copying and pasting the known correct password. So I SSH on instead , which by the way required using:

ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 root@192.168.3.1

When I SSH on I try to connect to the wifi again and get this output:

> Connecting to <SSID> network using intf 1...
> Checking wwan device status...
> wwan is up
> Checking internet connection...
> ERROR: request timeout, internet connection not successful
> Done!
root@Omega-2739:~# ping google.com
PING google.com (216.58.213.14): 56 data bytes
64 bytes from 216.58.213.14: seq=0 ttl=116 time=24.342 ms
64 bytes from 216.58.213.14: seq=1 ttl=116 time=21.777 ms
^C
--- google.com ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 21.777/23.059/24.342 ms

So I know I'm connected to wifi contrary to the check's output.

With this in mind, I try to upgrade it using oupgrade. This results in:

root@Omega-2739:~# oupgrade
> Device Firmware Version: 0.0.1
> Checking latest version online...
> ERROR: request timeout, internet connection not successful

But we know the connection is fine.

So I try to update the package manager to see if maybe that gives me some more information and indeed I get something more concrete:

root@Omega-2739:~# opkg update
Downloading http://downloads.openwrt.org/chaos_calmer/15.05/ar71xx/generic/packages/base/Packages.gz.
Updated list of available packages in /var/opkg-lists/chaos_calmer_base.
Downloading http://downloads.openwrt.org/chaos_calmer/15.05/ar71xx/generic/packages/base/Packages.sig.
Signature check passed.
Downloading http://downloads.openwrt.org/chaos_calmer/15.05/ar71xx/generic/packages/onion/Packages.gz.
Downloading http://downloads.openwrt.org/chaos_calmer/15.05/ar71xx/generic/packages/onion/Packages.sig.
Signature check failed.
Remove wrong Signature file.
Collected errors:
 * opkg_download: Failed to download http://downloads.openwrt.org/chaos_calmer/15.05/ar71xx/generic/packages/onion/Packages.gz, wget returned 8.
 * opkg_download: Failed to download http://downloads.openwrt.org/chaos_calmer/15.05/ar71xx/generic/packages/onion/Packages.sig, wget returned 8.
root@Omega-2739:~# ping downloads.openwrt.org
PING downloads.openwrt.org (168.119.138.211): 56 data bytes
64 bytes from 168.119.138.211: seq=0 ttl=54 time=40.878 ms
64 bytes from 168.119.138.211: seq=1 ttl=54 time=40.895 ms
^C
--- downloads.openwrt.org ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 40.878/40.886/40.895 ms

On further inspection of the failed URLs, I see that if I go to https://downloads.openwrt.org/chaos_calmer/15.05/ar71xx/generic/packages/onion/Packages.gz I just get redirected to a not found page at archive.openwrt.org/chaos_calmer/etc.... So I backtrack that URL till I hit something and the part i hit is:

https://archive.openwrt.org/chaos_calmer/15.05/ar71xx/generic/packages/

This doesn't have the relevant directories to get the package.gz file.

Is there something else i can do to update my Omega?

https://downloads.openwrt.org/releases/19.07.8/targets/ar71xx/generic/
has the onion-omega images realeased on Mon Aug 2 02:29:04 2021

The 18.06.x version is available from:
https://downloads.openwrt.org/releases/18.06.9/targets/ar71xx/generic/

Thanks.