The Internet of Things (IoT) is brilliant for adding connected hardware to your smart home. These can be in the form of vacuum cleaners, IP security cameras, bulbs, sensors, and even a dishwasher. A problem with adding so many small devices to your home network is that they could be quietly ruining it for everything else. I'm talking sluggish network speeds, weird device names, and other telltale signs that one (or a few) of your IoT products are misbehaving.

Sluggish LAN performance

Speed tests say otherwise

Many IoT devices will connect and transfer data between themselves and the cloud while active and in use. Some of them will hog your local network even when nothing is seemingly happening, which can make everything feel that little bit slower than normal. The worst part is that it can prove somewhat challenging to pinpoint the cause since running a speed test on your connection will likely yield positive results, but as soon as the testing has completed, things go south yet again.

When setting up IoT devices, you must consider how much bandwidth they will use and when. This is especially important for wireless networks since the more clients online at any given time, the slower the overall Wi-Fi will be. This is why I recommend connecting as much as you can through Ethernet cabling and ensuring no IoT device will call home too often, clogging up your network. If you wish to seal the deal, use your firewall to block all traffic to these known destinations.

Random traffic spikes

Especially during the night

No one wants to see some random spike of data occur at any time of the day, let alone through the night when everything should be more or less powered down. That may not be the case with all IoT devices, since some of them prefer to run firmware update checks through the night or even upload telemetry data from your LAN. It could be something as innocent as a fresh software update being pushed to your device with numerous benefits, but it could also be the product phoning home to some server.

If you do spot one of your IoT devices sending more data through the night than it receives, there's a good chance it's doing something it shouldn't.

Flooding your LAN with names

Can't tell them apart

Quickly, tell me what ESP_05926 and ESP_01231 do and what makes each client different? Yeah, I didn't think so. If you see your DCHP server get clogged up with some weird client names, you're likely encountering a wave of IoT devices beyond what you'd typically expect. When adding these products to your LAN, you're opening it up to more than simply a smart TV, a couple of smartphones, and a PC and console or two. Some hardware may even connect twice, causing all sorts of headaches.

It's even worse when they don't broadcast a name and are simply labelled "Unknown", which makes troubleshooting connectivity issues or anything relating to the LAN all the more enjoyable on a late Sunday night. If the device can't even supply a name for your DHCP server to use, what good do you think the firmware will be? It makes for a frightful thought, especially when some devices will continue broadcasting (and be visible with a DHCP lease) even when toggled off.

The worst part about leaving device names like this is you won't be able to tell when a new device enters the fray, unless you keep tabs on how many leases are handed out or list everything currently connected to your LAN. Regardless of how all your smart home hardware is named, it's always a good idea to work with unique MAC addresses.

Spotting strange DNS requests

Your router is handling some dodgy requests

DNS requests aren't inherently bad. If your IoT hardware is making a few requests now and then, it's usually attributed to updates, maintaining cloud connections, and other normal tasks. But sometimes, you may notice increased latency across the board, some router CPU spikes, and failed lookups that could even result in some flooding. Weirdly enough, you could find that one of your IoT devices is unintentionally launching a DDoS attack on your network from within.

Be on the lookout for strange behavior, which could come in the form of super-frequent DNS lookups, known telemetry destinations, or endpoints you've never heard of and don't expect the client to communicate with.

IoT devices can be fun

But all these concerns set aside, IoT and smart home devices can be really fun to mess around with and incredibly powerful once fully integrated into the wider network. Throw Home Assistant into the mix, and you now have quite the capable smart home. I used to be of the mind that smart home products offer nothing more than inconvenience for setting them up, managing them, and troubleshooting when things go wrong. But I've grown to appreciate how they can really make a difference.

That said, I always do some homework before picking up new hardware and take the time to adequately test these devices before opening them up to the wider LAN. Always use VLANs and other measures to help segregate (and protect) your network from troublesome hardware and software.