how to install docker version 20.10.12-0ubuntu2~20.04.1 on Ubuntu 20.04.5

why I am not able to install docker.io version 20.10.12-0ubuntu2~20.04.1 on Ubuntu 20.04.5?
It was getting installed earlier successfully. Any idea how to debug it further to know what changed in Ubuntu repo? Looking for workaround of fix also.

root@Ubuntu:/home/ravi/# apt-get install -y --allow-downgrades --allow-change-held-packages --allow-unauthenticated --ignore-hold docker.io=20.10.12-0ubuntu2~20.04.1
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Version '20.10.12-0ubuntu2~20.04.1' for 'docker.io' was not found
root@Ubuntu:/home/ravi/ric-dep/bin#


root@Ubuntu:~# lsb_release  -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.5 LTS
Release:    20.04
Codename:   focal
root@Ubuntu:~# 
root@Ubuntu:~# 

I got indexing err also while updating apt repo

+ curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg
+ apt-key add -
OK
+ echo 'deb http://apt.kubernetes.io/ kubernetes-xenial main'
+ mkdir -p /etc/apt/apt.conf.d
+ echo 'APT::Acquire::Retries "3";'
+ apt-get update
Hit:2 http://security.ubuntu.com/ubuntu focal-security InRelease                                        
Get:1 https://packages.cloud.google.com/apt kubernetes-xenial InRelease [8,993 B]                       
Err:3 http://in.archive.ubuntu.com/ubuntu focal InRelease                                                                                                                                                 
  Temporary failure resolving 'in.archive.ubuntu.com'
Hit:4 http://in.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:5 http://in.archive.ubuntu.com/ubuntu focal-backports InRelease
Fetched 8,993 B in 21s (432 B/s)
Reading package lists... Done
W: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/focal/InRelease  Temporary failure resolving 'in.archive.ubuntu.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.