Waking up devices in Hass.io (Home Assistant)

This is a quick post on a challenge I had to overcome while integrating my SmartTV (an LG TV 55UJ620V) with Hass.io.

I wanted Hass.io to be able to turn on the TV (as such allowing automations to be built on top of it, or for example turning it on through a voice command via Google Assistant). As such I first resorted to using the Home Assistant Wake on LAN built in integration (https://www.home-assistant.io/integrations/wake_on_lan/). It kind of worked, but was not very reliable (perhaps 2 out of 5 times it would work).

I knew that by definition, the way that (Wake-up On LAN) WOL is implemented is inherently unreliable: essentially the target (dormant) device is expecting a frame with a specific pattern of bytes. If it receives that frame, it wakes up the host, otherwise nothing happens. The device will normally scan for that pattern of bytes in the frame regardless of the type of transport level protocol it may be on top of. In the case of WiFi in particular, there is the probability (high or low, depending on the network conditions) of that single frame not reaching the destination. This probability increases with the more hops we have in between.

With this Hass.io implementation I was requiring the magic packet to be sent from a host (the Raspberry Pi where I keep Hass.io running) that is in a separate router vlan, from where the TV is (these are connected via Ethernet and WiFi respectively):

Building a kick-ass home automation by reflashing the Sonoff devices with Tasmota and getting it all working with hass.io

For some time I have been gradually bringing more devices to my house, which are either designed or having features allowing these to be integrated to a home automation system.

In spite of all the concerns that can arise from bringing smart/connected devices to the place where you expect personal privacy to exist, the convenience of having these ends up speaking louder overall..

It all started with having a set of unrelated devices in the house, each featuring connectivity and some cloud-based features provided by the vendor. This is the case for the Xiaomi Rockrobo vacuum cleaner, the Sonoff switches, the multimedia devices such as the TV set (an LG smartTV), and also the Google Chromecast and Assistant devices.

Consumer grade WiFi gear - when fixing the root cause is not at reach

Some time ago, I had to improve the performance and coverage of my home network, so as to be able to use the several devices around the house flawlessly, regardless of the location. Some of these devices have a certain demand for consistent bandwidth, as is the case of the SmartTV for watching IPTV and Netflix, and others such as the smartphones and tablets.

As always I tend to be frugal with spending money in hardware, trying to go with what performs well and is just about enough for the job.

This led me to aim for WiFi gear that would both be somewhat popular and low cost, while at the same time having some hope of being hackable and reflashed to OpenWRT in the future. This was the reasoning when I decided to buy a couple of TP-LINK TL-WR841N routers (with v9 hardware at the time).

At first I set these up and played with the stock firmware, configuring one to play the roles of  NAT, DHCP, DNS, firewall and so on, and the other to act solely as a WDS repeater, allowing WiFi coverage to be extended to the rest of the house.