Angular4 giving 404 for json data that exists and is publicly serving

The in-memory-web-api will interfere with your "outside" requests. You need to remove that from your NgModule, since otherwise Angular is always trying to look in in-memory-web-api for your requests, which obviously doesn't exist in that place. So removing the equivalent of

InMemoryWebApiModule.forRoot(InMemoryDataService)

from your ngModule and that should clear it out! :)