Hi… This domain doesn’t actually resolve for me (from New York). Generally, you will need at least a freebie shared IPv4 address, 
, for the above URL to work.
Possibly I’m misunderstanding what you’re attempting, though…
What other ones have they tried, if any? debug.fly.dev is the best for this, since it rules out the possibility of it being your app that’s askew:
$ curl -i -H 'flyio-debug: doit' 'https://debug.fly.dev/'
The returned flyio-debug header has useful information about which edge you went through, which backend worker it contacted, etc., although the field names are rather cryptic.
If you can’t get through to that one at all, then posting mtr output can often help Fly.io infrastructure staff pinpoint where the exact network glitch is.
Hope this helps a little!