I've had quite a bit of trouble getting iOS "Instant Hotspot" to use my iPhone's LTE connection from my Mac over the years. "Personal Hotspot" worked fine, but I have to take my phone out of my pocket, unlock it, go into settings and turn it on manually each time. Not the end of the world by any means, but a hassle nonetheless given that I should be able to achieve the same result with just two clicks on my Mac. I could see my iPhone listed at the top of the Wifi network list on my Mac, but clicking it would just eventually return an error: "Failed to enable personal hotspot".
I figured Little Snitch rules might have been partially responsible, but I hadn't been able to figure it out until today. I didn't find any similar threads here, so in case it helps anyone else, here's what I did:
- In Little Snitch, I set a rule to "Allow any outgoing connection" for identityservicesd
- In Keychain, I deleted all Airport passwords associated with my iPhone's hotspot
Elsewhere on the web, folks recommend logging out of iCloud on both devices, resetting iPhone network settings, restarting both devices, and renaming the iPhone's hotspot network. None of those steps ever worked for me, but you may want to try that if the above aren't enough to get it working.