Information
The DISCOVER_INST parameter specifies whether the instance can be discovered in the network. It is recommended that instances not be discoverable.
Rationale:
Discovery capabilities may be used by a malicious entity to derive the names of and target Db2 instances.
Solution
Attach to the Db2 instance:
db2 => attach to <db2instance>
Run the following command:
db2 => update database manager configuration using discover_inst disable