MikroTik

Is there anyway to upload a custom default config?

For example, when you reset the router to defaults, it loads a custom configuration?

This may be a stupid question but I couldn't find an answer on the forums.

Yes. It is possible to upload a script during netinstall. When running netinstall check the box for configure script and browse to the script file.

Yes, and also, this uploaded file will become the default config that is applied upon reset