The Router Setting That Broke EE Wi‑Fi Calling
A short networking field note on tracing an iPhone Wi‑Fi Calling failure to IPsec passthrough after a router upgrade.
Archive note: Originally published on Mullener in 2015. The exact behaviour belongs to an iPhone 6, EE and an Asus RT-AC68U in 2015; modern devices and carrier implementations may behave differently.
I replaced an ageing DrayTek 2820n with an Asus RT-AC68U to improve the Wi‑Fi at home. The wireless network improved, but EE Wi‑Fi Calling on my iPhone 6 stopped working.
That timing was the clue. The phone and mobile account had not changed; the router had. During setup I had disabled several features I did not expect to use, including VPN-related helpers.
Re-enabling IPsec Passthrough restored Wi‑Fi Calling immediately.
Why it made sense
Wi‑Fi Calling needs a secure path from the handset, through NAT on the home router, to the mobile operator’s network. In this implementation, disabling the router’s handling for IPsec traffic prevented that path from being established.
The useful troubleshooting sequence was small:
- Identify the last known-good state.
- List what changed at the boundary—in this case, the router and its configuration.
- Concentrate on settings capable of affecting encrypted or NAT-traversing traffic.
- Change one candidate setting and retest.
This is not a recommendation to enable every legacy “passthrough” option on every router. It is a reminder that an apparently application-level symptom can be caused by a network edge silently blocking the application’s secure transport.