# LANG=C apt update
...
Err:18 http://ftp.spline.de/pub/siduction/extra unstable Release
Unable to connect to ftp.spline.de:http:
Err:19 http://ftp.spline.de/pub/siduction/fixes unstable Release
Unable to connect to ftp.spline.de:http:
Reading package lists... Done
E: The repository 'http://ftp.spline.de/pub/siduction/extra unstable Release' does no longer have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://ftp.spline.de/pub/siduction/fixes unstable Release' does no longer have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
...
Siduction repo corrupt or spline server out of order?
http://www.downforeveryoneorjustme.com/ftp.spline.de (http://www.downforeveryoneorjustme.com/ftp.spline.de)
It's not just you! http://ftp.spline.de (http://ftp.spline.de) looks down from here.