I had an issue where Wi-Fi Calling (VoWiFi) worked on other Wi-Fi networks but would not activate on my home network.

My setup:

• iPhone with Claro Colombia
• Omada gateway and access points
• Two Pi-hole instances handling DNS for the LAN
• No custom Omada Gateway ACL rules affecting outbound traffic

At first, I suspected a firewall issue: IPsec pass-through, UDP ports 500/4500, NAT, or an Omada ACL rule. However, the gateway had no deny rules and there was no evidence that outbound traffic was being blocked.

The actual problem was Pi-hole blocking a required DNS record.

How I found it

I opened the Pi-hole Query Log, filtered the results by my iPhone’s LAN IP address, and searched for epdg.

I found repeated blocked DNS requests for:

epdg.ims.mnc101.mcc732.pub.3gppnetwork.org

This is the Claro Colombia ePDG hostname. ePDG stands for Evolved Packet Data Gateway; the phone uses it to discover the carrier endpoint needed for Wi-Fi Calling.

Because Pi-hole blocked the DNS lookup, the iPhone could not establish VoWiFi while connected to my home network.

Fix

I added this exact domain to the allowlist on both of my Pi-hole servers:

epdg.ims.mnc101.mcc732.pub.3gppnetwork.org

In Pi-hole, I went to:

Domains → Add domain → Add to allowed domains

I used an exact allow entry, not a wildcard.

After allowing the domain, I reconnected the iPhone to Wi-Fi, toggled Airplane Mode/Wi-Fi, and Wi-Fi Calling activated immediately.

Troubleshooting advice

If Wi-Fi Calling works on other Wi-Fi networks but not at home, check Pi-hole before opening ports or changing firewall rules:

1. Find your phone’s LAN IP address.
2. Open Pi-hole Query Log.
3. Filter the log by that IP.
4. Search for epdg.
5. Also search for ims and 3gppnetwork.org.
6. If Pi-hole blocks an ePDG domain, allowlist the exact FQDN on every Pi-hole or DNS resolver the phone may use.

Do not copy my Claro Colombia hostname blindly. Each carrier may use a different ePDG hostname.

In my case, no port forwarding, firewall changes, Omada ACL rules, or timeout changes were needed. The entire issue was a blocked DNS query.