5 simple network tests that fix most smart home issues

Building a smart home is typically a work in progress. Your home network is responsible for accessing and managing a variety of smart home devices. Whether you use Home Assistant or any other smart home software, you might run into network issues as the volume of devices grows. Network reliability is crucial to ensure that your smart home and automations work smoothly.
Those smart home devices, at times, turn radio silent, keep dropping connections, or become unresponsive. Resetting the device would help, unless the issue lies in the network configuration and setup. After checking the Wi-Fi signal strength with a Wi-Fi analyzer app and testing the connection speed for reliability, it’s necessary to roll up sleeves. Here are some simple network tests that will help you fix most smart home issues.
Performing a sanity check of DNS
Switch to Unbound for better results
Many continue to use ISP-provided DNS or switch to popular public DNS providers. But that comes at the cost of privacy and control. Consider switching to Unbound for better control of your smart devices and to avoid revealing any activities to third parties. Of course, that bars smart gadgets that require a dedicated cloud service.
Switching to Unbound as a recursive resolver will help you with detailed logs and records of the DNS traffic. That can help you audit the queries from smart home devices and then debug them. The only thing is that Unbound requires a little warm-up and time to collate the DNS traffic data. It’s quite useful if most of your smart home devices don’t rely on cloud services for automation or staying online.
Vetting the DHCP leases for smart devices
Ensuring there are no IP address conflicts
With a large volume of smart devices that require IP addresses, it’s necessary to ensure that the DHCP server is working as expected. Check your router’s interface to get a table consisting of hostname, IP address, MAC address and time left when looking for DHCP leases. The connected networking and smart home devices would appear on that table. Alternatively, you can ping your router’s DHCP server from another machine to check whether it’s reachable. Download and use the dhcping tool on Linux or macOS to ping the DHCP server directly with dhcping -s
For further troubleshooting, enable SSH on your router, log in from a different machine through Terminal, and check the DHCP leases file log saved by the router. The command and location of the lease file may differ based on your router’s make and custom firmware. ASUS router owners can check for DHCP leases for dnsmasq in /var/lib/misc directory after enabling full logging of all kinds of reports.
Watch out for multicast flooding along the network
Conserve network resources by reducing congestion
While you may want your smart lights, smart bulbs, or smart cameras to appear across machines on your home network. However, that often disrupts device discovery protocols and becomes undiscoverable. Of course, you’ll first need to check if IGMP Snooping is enabled on your router. To test whether such smart devices aren’t flooding the multicast traffic across the network, you can test that using Avahi and tcpdump utility. On Linux and macOS, installing avahi-daemon and avahi-utils will let you detect and inspect the multicast flooding across the network.
After installing Avahi, run the avahi-browse -a –resolve command to list out the multicast devices by IP address, if assigned. You can also simulate a multicast flood using the sudo tcpdump -ni any udp port 5353 -vv command to view the details of devices causing multicast chaos on your network.
Detecting and diagnosing broadcast storm of devices
Prevent network performance degradation
Often, misconfiguration causing network loops results in a broadcast storm, leading to a massive flood of packets in a short period of time. That cripples your network slowly and also degrades its performance over time. One example is two or more physical connections between devices on the same VLAN, which will cause packets to replicate indefinitely.
If you prefer using Terminal, run the sudo tcpdump -eni eth0 ether broadcast or ether multicast or vlan command to include details such as multicast, broadcast, and even VLANs over the network. Your network may be experiencing broadcast storms if you see hundreds of packet details per second. Wireshark is also a good option for less cumbersome diagnosing of broadcast storms.
Enabling IGMP Querier for effective multicast traffic management
Without it, multicast traffic may flood VLAN ports
Along with enabling IGMP snooping, it’s necessary to enable the IGMP querier setting on the network switch (L3) or the router, if available. Without a querier, multicast flooding will continue to affect all ports across your VLANs, leading to connectivity drops. In the absence of a network switch, a Linux-based gateway working as an IGMP Proxy can act as a querier.
To check if your network has the querier enabled, run sudo tcpdump -i eth0 igmp command from a machine. If you get no response, then the querier is not available, and that wouldn’t prevent multicast flooding even if you have IGMP snooping enabled.
Detailed logging helps diagnose smart home issues better
Besides the router logs, the details from your smart home software and other network devices can help pinpoint the issue with your smart devices. Irrespective of the volume and density of smart devices in the home, it is good practice to run such network tests to determine their reliability. While it does help to segment all your smart home devices into a dedicated VLAN, you need to ensure appropriate isolation levels before grouping them.