Intermittent WiFi Calling Issues

[michael_h014h2t]

Are there any setting or protocol configurations I should be sensitive to for iPhone and/or AT&T phones to ensure WiFi calling service?

I am running two R500s Unleashed.  They  are on v200.7.10.102.64.  My firewall/router is a Netgate SG-3100 running pfSense v2.4.4p3 on FreeBSD 11.2p10.

I have two AT&T iPhones on this infrastructure that when making WiFi calls, the person they are calling can't hear them.  The caller can hear who they are calling.  The issue is intermittent in that it doesn't happen on every call, but when it happens, it happens for the duration of the call.  These are the only such phones on this infrastructure, so I have no AT&T iPhones that do not experience this issue.  I do have two Android phones, one AT&T and one Verizon, which do not experience this issue on this infrastructure.  When I turn WiFi calling off on the two AT&T iPhones, the issue does not recur, so I am confident it is the WiFi calling.  The intermittent nature could be tied to when it is using WiFi versus when it is using cellular, I honestly don't know.  The two users only report issues on this infrastructure, nowhere else.  Signal is typically Excellent but sometimes Moderate and rarely Poor.  This issue has been often when a user is sitting next to the AP they are connected to.

This has been a very difficult issue to track down, and I don't know if it is related to Ruckus, pfSense, AT&T or something else, so I am now reaching out in all directions.  Any advice is greatly appreciated.  I'm happy to post more info if needed.

Thanks.