--- title: I segmented my smart home network and broke everything... description: Segmenting a smart home onto a dedicated IoT VLAN often breaks device discovery for protocols like HomeKit, Google Cast, and Matter because they rely on mDNS... canonical: https://daily.dev/posts/i-segmented-my-smart-home-network-and-broke-everything-until-i-fixed-these-three-settings-qkl5yl8ms twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: I segmented my smart home network and broke everything until I fixed these three settings | daily.dev og:description: Segmenting a smart home onto a dedicated IoT VLAN often breaks device discovery for protocols like HomeKit, Google Cast, and Matter because they rely on mDNS... og:url: https://daily.dev/posts/i-segmented-my-smart-home-network-and-broke-everything-until-i-fixed-these-three-settings-qkl5yl8ms og:image: https://api.daily.dev/og/posts/Qkl5yl8ms.png og:image:alt: I segmented my smart home network and broke everything until I fixed these three settings og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # I segmented my smart home network and broke everything until I fixed these three settings **[XDA Developers](https://daily.dev/sources/xda-developers)** · 4 min read · 0 upvotes · 0 comments ## Summary Segmenting a smart home onto a dedicated IoT VLAN often breaks device discovery for protocols like HomeKit, Google Cast, and Matter because they rely on mDNS multicast broadcasting, which doesn't cross VLAN boundaries by default. Three fixes address this: enabling an mDNS repeater/reflector (e.g., in UniFi's Global Network Settings) to relay multicast DNS across subnets, enabling IGMP snooping with a properly designated querier so multicast group membership doesn't silently expire, and disabling Wi-Fi client isolation while enabling multicast enhancement on IoT access point profiles along with a stable 2.4GHz beacon rate. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why do my smart home devices stop working after I put them on a separate IoT VLAN? Protocols like HomeKit, Google Cast, Spotify Connect, and Matter rely on mDNS broadcasting over UDP port 5353 to a multicast group, and multicast traffic doesn't cross VLAN boundaries by default. This breaks device discovery between your phone or PC on one VLAN and IoT devices on another, since the broadcast never reaches the other subnet. _Anyone segmenting a smart home network can track these networking gotchas on daily.dev before they cause outages._ ### How do I fix mDNS discovery breaking across VLANs in UniFi? Enable UniFi's built-in mDNS repeater by going to Settings, then Networks, then Global Network Settings, and toggling on Multicast DNS. A true mDNS repeater rewrites TTL and reads broadcasts on specific interfaces, resolving roughly 80% of missing device discovery issues without needing to open firewall holes between VLANs. _Developers troubleshooting cross-VLAN discovery issues can find setup specifics like this on daily.dev._ ### Why does smart home casting work for a few minutes then stop until I reboot the switch? This happens when IGMP snooping is enabled but there's no active IGMP querier, a designated router or switch that periodically polls the network asking who wants a given multicast group. Without a querier, the switch's multicast membership table expires after a few minutes, silently killing casting and local control until a reboot resets it. _Anyone debugging flaky multicast behavior on managed switches can dig into fixes like this on daily.dev._ ## Similar posts on daily.dev - [My smart home got more reliable when I moved it to a separate VLAN, not just more secure](https://daily.dev/posts/my-smart-home-got-more-reliable-when-i-moved-it-to-a-separate-vlan-not-just-more-secure-l9fhgr1wa) · XDA Developers · 0 upvotes · 0 comments - [I built a perfectly segmented home network, then spent six months poking holes back through it](https://daily.dev/posts/i-built-a-perfectly-segmented-home-network-then-spent-six-months-poking-holes-back-through-it-vgky0ahau) · XDA Developers · 0 upvotes · 0 comments - [Network segmentation is the smart home security step nobody talks about](https://daily.dev/posts/network-segmentation-is-the-smart-home-security-step-nobody-talks-about-0vihlne2o) · XDA Developers · 0 upvotes · 0 comments - [Moving cheap IoT gear to a guest network solved more problems than I expected](https://daily.dev/posts/moving-cheap-iot-gear-to-a-guest-network-solved-more-problems-than-i-expected-1jyf1thkt) · XDA Developers · 0 upvotes · 0 comments - [Your switch's management VLAN is sitting on the same network as your smart plug, and that's a massive security problem](https://daily.dev/posts/your-switch-s-management-vlan-is-sitting-on-the-same-network-as-your-smart-plug-and-that-s-a-massiv-2bzjv8vb3) · XDA Developers · 0 upvotes · 0 comments --- Tags: [#tech-news](https://daily.dev/tags/tech-news), [#networking](https://daily.dev/tags/networking) [View this post on daily.dev](https://daily.dev/posts/i-segmented-my-smart-home-network-and-broke-everything-until-i-fixed-these-three-settings-qkl5yl8ms) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"I segmented my smart home network and broke everything until I fixed these three settings","url":"https://daily.dev/posts/i-segmented-my-smart-home-network-and-broke-everything-until-i-fixed-these-three-settings-qkl5yl8ms","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/i-segmented-my-smart-home-network-and-broke-everything-until-i-fixed-these-three-settings-qkl5yl8ms"},"datePublished":"2026-09-01T17:05:04.677Z","dateModified":"2026-09-01T17:43:04.411Z","description":"Segmenting a smart home onto a dedicated IoT VLAN often breaks device discovery for protocols like HomeKit, Google Cast, and Matter because they rely on mDNS...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/1782f7e4a5eb91d0f1afb087a5c222e5?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/1782f7e4a5eb91d0f1afb087a5c222e5?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"XDA Developers","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"XDA Developers","logo":"https://media.daily.dev/image/upload/s--kCg6yyAP--/f_auto,q_auto/v1774964407/logos/xda-developers?_a=BAMAMiWQ0","url":"https://daily.dev/sources/xda-developers"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/i-segmented-my-smart-home-network-and-broke-everything-until-i-fixed-these-three-settings-qkl5yl8ms","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"tech-news,networking","timeRequired":"PT4M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"XDA Developers","item":"https://daily.dev/sources/xda-developers"},{"@type":"ListItem","position":3,"name":"I segmented my smart home network and broke everything until I fixed these three settings"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/i-segmented-my-smart-home-network-and-broke-everything-until-i-fixed-these-three-settings-qkl5yl8ms#faq","mainEntity":[{"@type":"Question","name":"Why do my smart home devices stop working after I put them on a separate IoT VLAN?","acceptedAnswer":{"@type":"Answer","text":"Protocols like HomeKit, Google Cast, Spotify Connect, and Matter rely on mDNS broadcasting over UDP port 5353 to a multicast group, and multicast traffic doesn't cross VLAN boundaries by default. 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