Reviewing this it appears ARC is not configuring itself automatically to work outside the home. I’d suggest you open a post in support category (or maybe a mod can move this). Solving this will require “jargon” however. When ARC does not automatically configure itself there can be thousands of reasons and narrowing down the problem requires at least some jargon.
You can try looking through this known list of things which others have done to work with specific hardware and Internet service providers.