Why Does iPhone Stop Responding to Local Network Pings When Using Cellular Internet?

Question

Why Does iPhone Stop Responding to Local Network Pings When Using Cellular Internet?

I have an iPhone connected to a Raspberry Pi via a USB Ethernet adapter. The iPhone is assigned a static IP address (192.168.1.3 for IPv4 and a link-local IPv6 address). The Raspberry Pi is configured with no gateway on the Ethernet connection since I want the iPhone to use its cellular connection for internet access.

Here's the issue:

The iPhone can initially respond to pings (IPv4 and IPv6) from the Raspberry Pi.
However, when I open Safari or other apps that use the cellular connection, the iPhone stops responding to pings from the Raspberry Pi. Local network traffic seems disrupted.

Questions:

Why does iOS change its routing behavior when using cellular internet, even though no gateway is assigned on the USB Ethernet interface?
How can I ensure the iPhone consistently responds to local network traffic over the USB Ethernet adapter while maintaining internet access via cellular?

Any insights or guidance would be appreciated. Thank you!

Posted on Jan 27, 2025 05:33 PM

Reply

Answer 1

Top-ranking reply

Lawrence Finch

Community+ 2025

Level 10

226,726 points

Jan 27, 2025 06:26 PM in response to caryfromtoronto

If you don’t have a Wi-Fi connection to the internet on the iPhone it will always use cellular data when accessing the internet, and ignore the local network.

Another possibility: Do you have a 3rd party VPN installed, even if you are not using it? If so, delete the VPN profile in Settings/General/VPN & Device Management/VPN. Don't just turn it off; delete the profile. If that fixes it, you can try reinstalling VPN.

Reply

Why Does iPhone Stop Responding to Local Network Pings When Using Cellular Internet?

Similar questions