With REHL 9 and AlmaLinux 9 and presumably other RedHat derivative, DES is no longer available for net-snmp communication. DES or Data Encryption Standard is an old encryption standard and has been superseded by AES.

So when you try running snmpwalk with “-x DES” option, you get the following error

Invalid privacy protocol specified after -3x flag: DES
USAGE: snmpwalk [OPTIONS] AGENT [OID]

  Version:  5.9.1

To fix the issue, you’ll need to upgrade your devices to AES.

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/considerations_in_adopting_rhel_9/assembly_shells-and-command-line-tools_considerations-in-adopting-rhel-9#ref_changes-to-system-management_assembly_shells-and-command-line-tools

https://serverfault.com/questions/1119288/snmp-des-algorithm-no-longer-working