Phone on different subnet shown as away

[steelman231]

Version: 2.4.1

Hi.
My HA are on subnet 192.168.20.xx and my phone are on 192.168.0.xx. At the time there are no restrictions between the two vlans.

When I add the phone to IPhone Device Tracker and have the box checked in "Check if IP is in a reachable Subnet" I'll receive the error "IP not in range of HASS subnets".

But if I leave the checkbox unchecked, the phone gets added to the integration. BUT constantly status "away".

How come?

I tried this comment but it didn't change anything...

[keisersuze]

I am also interested in this.

[LordValgor]

I three am interested in this. mDNS is configured to traverse both VLAN's as well.

[zajaaczki]

Same issue for me It does not work with vlans and enabled mDNS, iphone is reachcble from HA.

[superkekko]

Hi, I'm interested too.I need to know witch mDNS I need to enable, someone know that?

[LelleB]

Same problem here as well, including checkbox for subnets. mDNS is working between VLANs, but all phones are "away".

[f45tb00t]

The issue is, that arp is used.

Version: 2.4.1

Hi. My HA are on subnet 192.168.20.xx and my phone are on 192.168.0.xx. At the time there are no restrictions between the two vlans.

When I add the phone to IPhone Device Tracker and have the box checked in "Check if IP is in a reachable Subnet" I'll receive the error "IP not in range of HASS subnets".

But if I leave the checkbox unchecked, the phone gets added to the integration. BUT constantly status "away".

How come?

I tried this comment but it didn't change anything...

Placing Home Assistant into multiple subnets or VLANs in order to make ARP, mDNS, or ping-based presence detection work is architecturally unsound and weakens network segmentation.
A multi-homed application host becomes a de-facto zone crossover point, increasing attack surface and enabling lateral movement between security zones. This breaks intended trust boundaries and makes policy enforcement significantly harder.

To avoid this in my setup, I chose a different approach. Instead of adding additional interfaces or using Home Assistant add-ons for presence detection, I use my OpenWrt access points to generate presence events and forward them to Home Assistant via MQTT.

This keeps Home Assistant in a single security zone, preserves proper network segmentation, and provides immediate, event-based presence detection without polling or subnet hacks. The solution is lightweight and leverages the network infrastructure as the authoritative source, which I consider critical from a security perspective.

If you are using OpenWrt and MQTT, you may want to give this approach a try. https://github.com/f45tb00t/OpenWRT_HA_Presence