I would like to give another update. For over a month I was getting some pretty reliable WiFi calling on my iPhone 12 Pro when having both "Forbid IGMP Proxy Service" and "Forbid Fingerprint Service" checked in the beta options. I disabled the "Forbid Fingerprint Service" due to some known issues with houses using Philips Hue and LiFX bulbs, so whether it made any improvement to WiFi calling is purely incidental. But there are some catches to this.

First, I only have luck when my phone is using the 2.4GHz radio. The 5GHz radio continues to give me WiFi calling issues. Secondly, if I leave the house and come back home, it does take more than a few minutes before my phone will confirm that WiFi calling is enabled and working properly. So it is not as instantaneous as my older router was and prevents me from "hot swapping" between cellular and my WiFi and keeping the call from dropping.

Today was the first time I heard my wife complaining of constant dropped calls on her iPhone X. Sure enough, it wasn't holding the WiFi calling and she was on the 5GHz radio. I forced her to join the network on the 2.4GHz radio and after a number of minutes and a phone restart it started to work fine.

I did notice during these issues that there was a newer firmware update out, 3.5.0rc5 and decided to upgrade to it today (albeit reluctantly). I was on 3.4.3 earlier when the issues above were happening. I can't say much if the newer firmware update resolves my problems since it is still too early to tell.

Needless to say, this is extremely frustrating. I am going on 6 months now since buying the Amplifi Alien and I am STILL having WiFi calling problems across multiple iPhones. With us working from home and not having a strong enough cell signal to depend on that, this has become way more than just an inconvienence.

On a somewhat side note of other issues, I have noticed with my iPhone if I stray too far away from the router when on the 2.4GHz radio to have weak, but still connected signal, when I get back to a stronger signal the phone's speed and responsiveness doesn't always improve. After doing this, I have had instances where when I am back within 10ft of the router my response time will be in the seconds (not milliseconds) and my throughput will barely top 5Mbps. To fix the problem, I either have to change to the 5GHz radio and back or restart my phone.

WiFi Calling On iPhone's