Hi @pebbletech! My guess is that this is not an issue with your configuration. Rather, it appears that when you connect to Fly.io IP addresses, your internet service provider is sending the traffic to the ams region as opposed to a closer one. Our proxy in ams then has to forward your requests all the way back to the running instance of your app in sin.
(You can also check the fly-request-id HTTP header on responses from your API. The region code at the end of it is the region where your request was received. I suspect that it will be ams.)
Unfortunately, this kind of thing happens with some frequency, but we can sometimes adjust the routing information that we announce to get ISPs to pick better routes. If you’re comfortable providing any information about your location/ISP or sharing traceroute output from your location to your app (like in the first thread I linked to above), we may be able to look into it.