The script name for 3006.102 Merlin firmware is /jffs/scripts/stubby-sdn.postconf. Are you running Merlin or stock firmware? Stock firmware doesn’t have this feature.
Generally the configuration files, stubby-INDEX.yml.add and stubby-sdn.postconf, discussed in this topic are for Asus-Merlin 3006.102.x firmware NOT for Asus stock firmware. Trying to use coding or file naming that is specific to Asus-Merlin firmware may cause unexpected results, or will not work at all, when used on stock Asus firmware.
To avoid confusion, since you are using stock Asus firmware, you should continue with Jacklul in the other thread you are posting in about your issue since that discussion (Collection of scripts for stock firmware) deals specifically with Jack's Custom scripts for stock ASUS routers which it appears you may be trying to use.