https://matt-ellis.dev/tags/networking/Recent content in Networking on Matt EllisHugoen-GBThu, 29 Oct 2026 11:00:00 +0000https://matt-ellis.dev/posts/debugging-iot-with-tcpdump/Thu, 29 Oct 2026 11:00:00 +0000https://matt-ellis.dev/posts/debugging-iot-with-tcpdump/<p>I recently had underfloor heating installed with a Wunda Smart HubSwitch. The hub refused to finish setup, insisting it had no internet connection. My network disagreed. This is the story of working out who was right, mostly by reading packets.</p> <h2 id="the-setup">The setup</h2> <p>My home network is a slightly mixed bag:</p> <ul> <li><strong>Ubiquiti UniFi access points</strong> (including a U6 Pro in the kitchen), managed by the UniFi controller with a third-party gateway</li> <li><strong>A TP-Link Omada router</strong> doing routing and DHCP</li> <li><strong>A dedicated IoT VLAN</strong> (VLAN 107, <code>192.168.107.0/24</code>) with its own SSID, broadcast on 2.4 GHz only, because most smart home devices still can&rsquo;t do 5 GHz</li> </ul> <p>The UniFi APs tag IoT traffic with VLAN 107 and hand it to the Omada router, which does everything else.</p>