(Already asked this question at Webmasters Stack Exchange, but I’m not sure that’s the right place for it)

I’m having trouble setting up Umami analytics with subdomains. Here’s my scenario:

At example.com, I serve my product website that advertises my service. This site includes my marketing content and ad landing pages, etc. However, serve my actual webapp over at app.example.com. I want to track users across the boundary between my app and my website, so I can, for example, see user journeys from the website to the app.

I tried just using the same Umami website ID on the root site and subdomain. As far as I can tell, though, Umami doesn’t differentiate between https://example.com/ and https://app.example.com/—they both appear as /.

I found many similar questions, but they all are specific to Google Analytics.

I’m new to Umami and analytics in general. What am I missing here? Do I need to create a custom tracker function for this usecase, sending a custom value for url that includes the subdomain? Or is this an unsupported setup?