Originally Posted by
Spaz888 Wi-Fi calling works with exceptions. It doesn't ALWAYS work in standby mode. It does about 20% of the time.
Thanks for the link to the ports the iPhone uses! The ports the iPhone uses are UDP 500 and 4500. I have no idea how to verify if either of them are blocked or if they randomly get blocked.
I don't recall having this issue with iOS 12.
While I can’t help you with specifics, I would check that one of these settings are enabled (Different names on the same feature):
- IPSec Passthrough
- IKE Passthrough
- IPSec Application Level Gateway (ALG)
- IKE ALG
What these do (simplified) is rewrite the contents of an IPSec datagram with the public IPv4 address and then send it, instead of just sending it as is. They are usually enabled on consumer equipment, and disabled on prosumer and entreprise equipment
Another thing that might be happening is that the connection does not have enough traffic and it is timing out. That’s something I cannot help with.