From the SNMP Agent Assertion User guide which is compatible with API Gateway 11.0, it is relevant for Debian BullsEye, but with Gateway 11.1 the OS version changes to Debian Bookworm.
The part in the User guide which talks about updating SNMP will not work.
With the current contents of the /etc/apt/sources.list file, it is trying to do updates for Debian Bullseye, whereas the latest patches installed on 11.1 make it Debian Bookworm, so the updates are from an older version of Debian.
What needs to be configured in the /etc/apt/sources.list file for Debian Bookworm?
CA API Gateway 11.1
Changes on the Debian OS version from bullseye to bookworm
Edit the /etc/apt/sources.list file and to add the following lines:
deb http://ftp.us.debian.org/debian/ bookworm main contrib non-free
deb http://deb.debian.org/debian bookworm main contrib non-free
deb-src http://deb.debian.org/debian bookworm main contrib non-free
deb http://security.debian.org/debian-security/ bookworm/updates main contrib non-free
deb-src http://security.debian.org/debian-security/ bookworm/updates main contrib non-free
deb http://deb.debian.org/debian bookworm-updates main contrib non-free
deb-src http://deb.debian.org/debian bookworm-updates main contrib non-free
This will allow you to download any official Debian hosted packages. Once the download and installation is complete, you can clean up the file to avoid any future downloads/installs.