--- title: My managed switch had a port isolation feature I... description: A managed switch's port isolation feature complements VLANs by stopping IoT devices within the same VLAN from communicating with each other, reducing the blast... canonical: https://daily.dev/posts/my-managed-switch-had-a-port-isolation-feature-i-ignored-and-it-finally-tamed-my-smart-home-devices-kjr0t3hnz twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: My managed switch had a port isolation feature I ignored, and it finally tamed my smart home devices | daily.dev og:description: A managed switch's port isolation feature complements VLANs by stopping IoT devices within the same VLAN from communicating with each other, reducing the blast... og:url: https://daily.dev/posts/my-managed-switch-had-a-port-isolation-feature-i-ignored-and-it-finally-tamed-my-smart-home-devices-kjr0t3hnz og:image: https://api.daily.dev/og/posts/kJR0T3HNz.png og:image:alt: My managed switch had a port isolation feature I ignored, and it finally tamed my smart home devices 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. # My managed switch had a port isolation feature I ignored, and it finally tamed my smart home devices **[XDA Developers](https://daily.dev/sources/xda-developers)** · 4 min read · 0 upvotes · 0 comments ## Summary A managed switch's port isolation feature complements VLANs by stopping IoT devices within the same VLAN from communicating with each other, reducing the blast radius if a smart plug or bulb gets compromised. VLANs alone only separate IoT traffic from trusted devices like NAS and laptops, but they don't stop lateral movement between untrusted IoT devices themselves. Port isolation forces all inter-device traffic through the router, but it breaks mDNS-based discovery (Chromecast, AirPlay, HomeKit, Sonos, printers), which requires setting up mDNS reflection rules to restore device discovery while keeping isolation in place. The recommended setup combines one VLAN for IoT devices, a firewall policy restricting VLAN traffic, and port isolation within that VLAN, with mDNS reflection for automations that need it. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Does putting IoT devices on a VLAN stop them from attacking each other? No, a VLAN only isolates one network segment from another, such as keeping IoT devices away from a NAS or PC. It does not prevent devices within the same VLAN from communicating with or attacking each other, since all devices in that segment can still talk directly to one another. _Anyone hardening a smart home network can find practical isolation setups discussed on daily.dev._ ### Why does port isolation break Chromecast, AirPlay, and HomeKit device discovery? Port isolation blocks the link-local multicast traffic used by mDNS, which Chromecast, AirPlay, HomeKit, Sonos, and network printers rely on for discovery. Because isolation forces all traffic through the router and blocks direct peer-to-peer communication between isolated ports, these discovery broadcasts never reach other devices, making them disappear from view unless mDNS reflection rules are added. _Developers troubleshooting mDNS and multicast quirks often compare notes on daily.dev before changing network configs._ ### What network setup combines VLANs and port isolation for IoT security? One effective approach uses a single VLAN for all IoT devices, a firewall policy restricting traffic between that VLAN and the rest of the network, and port isolation enabled within the IoT VLAN itself so devices can't reach each other directly. mDNS reflection is added back selectively for the few automations that require device discovery to keep working. _Those designing IoT-safe home networks can track configuration patterns 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 · 1 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 - [VLAN isolation sounds great until you forget the firewall rules that actually make it work](https://daily.dev/posts/vlan-isolation-sounds-great-until-you-forget-the-firewall-rules-that-actually-make-it-work-wod74ouxg) · XDA Developers · 0 upvotes · 0 comments - [One VLAN setting locked down my smart home and stopped every device from phoning home](https://daily.dev/posts/one-vlan-setting-locked-down-my-smart-home-and-stopped-every-device-from-phoning-home-v3opqjgdh) · XDA Developers · 1 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 --- Tags: [#tech-news](https://daily.dev/tags/tech-news), [#security](https://daily.dev/tags/security), [#iot](https://daily.dev/tags/iot) [View this post on daily.dev](https://daily.dev/posts/my-managed-switch-had-a-port-isolation-feature-i-ignored-and-it-finally-tamed-my-smart-home-devices-kjr0t3hnz) ```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":"My managed switch had a port isolation feature I ignored, and it finally tamed my smart home devices","url":"https://daily.dev/posts/my-managed-switch-had-a-port-isolation-feature-i-ignored-and-it-finally-tamed-my-smart-home-devices-kjr0t3hnz","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/my-managed-switch-had-a-port-isolation-feature-i-ignored-and-it-finally-tamed-my-smart-home-devices-kjr0t3hnz"},"datePublished":"2026-08-20T14:03:13.962Z","dateModified":"2026-09-13T20:46:22.498Z","description":"A managed switch's port isolation feature complements VLANs by stopping IoT devices within the same VLAN from communicating with each other, reducing the blast...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/0b5100ef2cf718df281384deee4f8c43?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/0b5100ef2cf718df281384deee4f8c43?_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/my-managed-switch-had-a-port-isolation-feature-i-ignored-and-it-finally-tamed-my-smart-home-devices-kjr0t3hnz","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"tech-news,security,iot","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":"My managed switch had a port isolation feature I ignored, and it finally tamed my smart home devices"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/my-managed-switch-had-a-port-isolation-feature-i-ignored-and-it-finally-tamed-my-smart-home-devices-kjr0t3hnz#faq","mainEntity":[{"@type":"Question","name":"Does putting IoT devices on a VLAN stop them from attacking each other?","acceptedAnswer":{"@type":"Answer","text":"No, a VLAN only isolates one network segment from another, such as keeping IoT devices away from a NAS or PC. 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