Thank you for helping this far, Now I am able to spot 1 difference between the unbound running and working on osboxes ubuntu and rockpi ubuntu
On my osboxes ubuntu 20.x
$ sudo unbound-control status
[sudo] password for osboxes:
version: 1.9.4
verbosity: 0
threads: 1
modules: 3 [ subnet validator iterator ]
uptime: 39284 seconds
options: reuseport control(ssl)
unbound (pid 846) is running...
I see options: reuseport control(ssl)
but on rockpi ubuntu I see
$ sudo unbound-control status
version: 1.6.7
verbosity: 1
threads: 1
modules: 3 [ subnet validator iterator ]
uptime: 89 seconds
options: control(ssl)
unbound (pid 19064) is running..
just options: control(ssl)
could it be this causing the problem.
I took a look at manpages:
https://manpages.debian.org/jessie/unbound/unbound.conf.5.en.html
tried so-reuseport: yes though didnt help