Ah, yeah, you can’t redirect based on things like authority or HTTP request type (but you can redirect based on hostname: see https://docs.netlify.com/routing/redirects/redirect-options/#domain-level-redirects for details). People who use that functionality “segregate” their proxy’d content on the remote service under a path that has no other content under it, so you could do something like this:
https://qrpu.sh/api/* https://remoteservice/:splat 200!
And yes, our CDN (proxying included) only handle HTTP requests, not websockets or anything else. We do handle streaming HTTP, but not for unlimited time - we couldn’t host e.g. youtube videos longer than a minute or so via proxying. I also understand that you may not want to rearchitect your backend to allow that pathing I describe, so hopefully the workaround I mentioned will work (add www as a domain alias, and have a custom domain set to a placeholder).
If that didn’t work, let me know. I will see if I can help you get it configured well, but if not, I can calso reate a special config to allow the SSL certificate to use www and not the bare domain, but it is rather inflexible, as you cannot later add additional names to the site without our help. Let me know if you’d like that (and if you want to keep the
foo domain alias if so, since we’ll need to allow for that during this configuration).