You are right. I traced the issue to DNS.
I am having issues with stubby for cloudflare DoT
When I disable stubby opkg update works fine.
But now the issue is why is stubby causing issues. Here are my settings (which work fine with my RPi3 OpenWrt router - instructions here):
Per those instructions, there's only 2 steps after installing stubby:
- "DNS forwardings"
- "Ignore resolv file"