Good tip. I just tried with both and wasn't routed to a faster point of presence with either.

I'll add a traceroute from the phone and one from a device connected to the LTE router to the updates section next.

It's definitely odd that you're getting routed across the country to an east coast pop. Ideally in your location you'd be routed to a west or central pop. Perhaps a bad combination of Cloudfront getting geolocation wrong for your IP range, and poor performance of at&t's network for that specific source-destination combination.

I found that odd as well, and my iPhone hotspot does get routed through a different list of hosts as you can see in the traceroute.

I suppose it should be noted. The iphone antenna and router antennas are no more than a meter from each other. They're unlikely to be hitting different towers.

What are you using for DNS?

On chrome-based mobile browsers your traceroutes are getting stuck in a small non scrollable iframe-type-thing.

Use resolvers that support eDNS Client Subnet, otherwise geo-resolvers like Google/CF DNS may cause your traffic to be misrouted.

You can use Quad9's EDNS [0] so your client is properly routed, any privacy concerns aside.

[0] https://www.quad9.net/support/faq/#edns

Quad9 doesn't work on AT&T, because of poor routing you're sent to Miami or Amsterdam.