To do this, you can set the resource-pack= line in the server's server.properties to a URL hosting an empty or default resource pack. This will effectively replace ItemsAdder's textures with the default ones. This method is less about portability and more about compatibility, but it is a valid technique for mixed-server networks.
An setup refers to either:
Open your plugins/ItemsAdder/settings/config.yml . This is where most people break portability.
"ItemsAdder Portable" refers to a structured, organized approach to managing your ItemsAdder configuration files ( contents folder) so they can be easily moved, backed up, or deployed to different servers (e.g., from a local development server to a production BungeeCord network) without re-configuring everything. Key Benefits of a Portable Setup
While not fully automatic, this guarantees players see your custom items even without an active internet connection.