HTTPS works with web browser but iOS app gives NSURLError -1004

I have a FQDN which points to my HAAS install which is using SSL. Everything works as expected outside of my network (both web and iOS) and everything works fine internally with a web browser, but on the iOS app, although the app can properly discover my HA instance, trying to connect to it yields a NSURLError -1004. I’m really not sure what’s going on here because a NSLOOKUP properly resolves the address.

I’ve read a ton of posts on this and tried many suggested solutions, but none seem to address this issue. Any help would be greatly appreciated.