Sveltekit app fails to respond

Honestly I'm not entirely sure if I'm doing this correctly, but I've got a SvelteKit app running (works fine locally) on a Railway service -- the build/deploy seem to work fine, but it appears to not be responding when I visit the URL. Would this have something to do with the port? I'm not sure what port to listen on if so

8a22e319-8a06-4810-9e75-4c3b7db0f8e7

Using vite preview for the start command

Alright well I'm not sure whether or not this was the correct solution, but adding the --host flag to yarn start appeared to fix the issue when listening on port 4173. However there's another "issue" now, which is the custom domain doesn't seem to persist on redirect, which I'm not sure whether or not that's the expected behavior

So if the custom domain is www.xyz.com, and the railway domain is railway.app, then going to www.xyz.com does take you to railway.app, but it changes the domain so it still appears a bit odd