repos still don't work

(target system is RNDU6000 with OS Version 6.10.8)

this post is a follow-up to my last post , which I created a year ago.

well, it's been a year, but nothing has changed: apt-get still doesn't work.

Step 1:

# cd /var/lib/apt/lists && rm -rfv * && apt clean && apt update && rn_shutdown -r

Step 2:

#apt-get update --fix-missing

Ign:1 http://security.debian.org jessie/updates InRelease
Ign:2 http://security.debian.org jessie/updates Release
Ign:4 http://security.debian.org jessie/updates/main amd64 Packages
Ign:5 http://security.debian.org jessie/updates/main all Packages
Ign:4 http://security.debian.org jessie/updates/main amd64 Packages
Ign:3 http://mirrors.edge.kernel.org/debian jessie InRelease
Ign:5 http://security.debian.org jessie/updates/main all Packages
Ign:4 http://security.debian.org jessie/updates/main amd64 Packages
Ign:5 http://security.debian.org jessie/updates/main all Packages
Ign:4 http://security.debian.org jessie/updates/main amd64 Packages
Ign:5 http://security.debian.org jessie/updates/main all Packages
Ign:6 http://mirrors.edge.kernel.org/debian jessie Release
Ign:4 http://security.debian.org jessie/updates/main amd64 Packages
Ign:7 http://mirrors.edge.kernel.org/debian jessie/main amd64 Packages
Ign:5 http://security.debian.org jessie/updates/main all Packages
Ign:8 http://mirrors.edge.kernel.org/debian jessie/main all Packages
Err:4 http://security.debian.org jessie/updates/main amd64 Packages
404 Not Found [IP: 151.101.86.132 80]
Ign:7 http://mirrors.edge.kernel.org/debian jessie/main amd64 Packages
Ign:8 http://mirrors.edge.kernel.org/debian jessie/main all Packages
Ign:5 http://security.debian.org jessie/updates/main all Packages
Ign:7 http://mirrors.edge.kernel.org/debian jessie/main amd64 Packages
Hit:9 https://apt.readynas.com/packages/readynasos 6.10.8 InRelease
Ign:8 http://mirrors.edge.kernel.org/debian jessie/main all Packages
Ign:7 http://mirrors.edge.kernel.org/debian jessie/main amd64 Packages
Ign:8 http://mirrors.edge.kernel.org/debian jessie/main all Packages
Ign:7 http://mirrors.edge.kernel.org/debian jessie/main amd64 Packages
Ign:8 http://mirrors.edge.kernel.org/debian jessie/main all Packages
Err:7 http://mirrors.edge.kernel.org/debian jessie/main amd64 Packages
404 Not Found [IP: 147.75.80.249 80]
Reading package lists... Done
W: The repository 'http://security.debian.org jessie/updates Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://mirrors.kernel.org/debian jessie Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://security.debian.org/dists/jessie/updates/main/binary-amd64/Packages 404 Not Found [IP: 151.101.86.132 80]
E: Failed to fetch http://mirrors.edge.kernel.org/debian/dists/jessie/main/binary-amd64/Packages 404 Not Found [IP: 147.75.80.249 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.