Right after installing Debian I got the following:
Error: The repository 'cdrom://[Debian GNU/Linux 13.1.0 _Trixie_ - Official amd64 DVD Binary-1 with firmware 20250906-10:24] trixie Release' does not have a Release file.
Notice: Updating from such a repository can't be done securely, and is therefore disabled by default.
Notice: See apt-secure(8) manpage for repository creation and user configuration details.
I fixed this by updating /etc/apt/sources.list as follows:
# deb cdrom:[Debian GNU/Linux 13.1.0 _Trixie_ - Official amd64 DVD Binary-1 with firmware ...] /
deb http://deb.debian.org/debian trixie main contrib non-free-firmware non-free
deb http://deb.debian.org/debian-security trixie-security main contrib non-free-firmware non-free
deb http://deb.debian.org/debian trixie-updates main contrib non-free-firmware non-free
sudo apt update
