HomeAssistant in two networks with different purposes (Ethernet/Wifi)

Installation
1

Hello to all,
I am not even new to HA, I don’t even have it, but I had some profound (sic) conversations about it with Gemini. I think of acquiring a HA Green for some tasks and think about the goodies I need and if it is going to work in my case, and if what I have in mind is even (easily) possible.
So, essentially, I have:

  • An ISP router (FritzBox) fairly modern, in my cellar plus an ethernet-wired repeater on my 2nd floor. They have both a guest network (WIFI+1 LAN port) which I use for my connected stuff so that it is not interfering with my home network (security). Devices can talk to each other (Wiz lamps) inside this network, which would be great for integrating HA there and talk to them, but IP addresses within it are random.
  • The one LAN port linked to the guest network is occupied by my Tado hub (thermostat + heating valves)
  • A couple of Wiz lightbulbs, already mentioned
  • Solar velux sunshades, but for the moment without app integration (needs a 100 EUR device which I was not willing to invest in yet)
  • A Huawei Inverter connected to the WIFI (no extra dongle), with battery and solar panels
  • A Zehnder ComfoFlex ventilation with two switches, luckily, because it only talks to its propretary app (contrary to ComfoQ which could be made to talk other stuff)
  • An outdated FritzBox lying around somewhere.

I want HA mainly to talk to my inverter and tell it when to feed electicity to the house, the battery or the grid depending on more complex parameters than Huawei’s own confusing interface (discharge some of the battery to the grid in the evenings when demand in my energy community is high, but spare some battery level for myself, discharge the rest of it to 5% into the grid in the mornings while demand is still high and sun does not shine yet - unless they announce a cloudy day, and all of this only between end-March and September when I can reasonably expect to charge to 100% during a day). A nicer energy dashboard than what Huawei provides would also be great.
Now if, at a later point, I can control my sunshades relative to outside temperature AND luminosity (or, even better, PV output as a proxy for luminosity, saving me an additional sensor), save my vacation programme for anti-theft lighting scenarios for when I need it and switch both lighting, ventilation and heating to holiday mode with a single gesture that would be great, but needs further elaboration).

Issue points: The inverter is on WIFI, not fixed IP address, HomeAssistant Green has no home WIFI but USB ports; separate networks between smart stuff and human activity

My idea: I setup my old FritzBox as a router with WIFI as a subnetwork of my home network, create some kind of firewall so that devices do not talk to my home network (but only the internet because they have to), connect HA+Tado via ethernet to the FritzBox, so that HA can talk to the inverter. Add a Zigbee dongle to have sensors such as outside temperature, maybe some consumption control in dumb appliances, when I feel like it a relay inside the ventilation to force vacation mode. Sounds fine, but I want to access HA with my devices in the home network (without cloud). So I thought adding a Wifi stick to HA to have a presence in the home network to access its interface and have the app talk to it directly.

Now, I read in several places that HA and Wifi isn’t such a great idea, but I have no idea why. I saw it is not meant to be a router, but in my case it isn’t, I just want the interface. Is it because it is difficult to configure different network interfaces and assign different ‘faces’ to them (the ethernet face talking to devices only, the wifi face interacting with humans only)?
Now my second question is, which inexpensive Wifi stick is good for that use? Obviously, it will not stream 4k, so just a basic stick should do, isn’t it?

Overall, does the setup seem logical and work to you who have more experience in fiddling around these things? Before I spent hours in my basement to set everything up during sunny days I could spend with my family, I’d know if this sounds reasonable.

Thanks!
Philippe

2

Ha is not designed with a multi homed network design in mind and most people I’ve seen try this fail. If you’re not ready to dig into router tables and speak IPv6… Probably not the way I’d go.

The answer to wifi… HA is a server you should not run a server on wifi, inherently requires more infra to stand up than plug it in. (immaterial for this disc.)

Best case doing this wired will be fragile of it works. Wifi. Good luck. Simplify your topology. Why not just a simple switch behind wherever that wifi hits your wired network. Where’s that.

3 Likes
3

If your power requirement is less than the maximum possible PV output available, you will be underestimating the luminosity. Also, solar irradiation has several components to it, like diffuse radiation, which means PV output may be high while luminosity will be comparatively low.

4

Thank you Nathan for taking the time to respond.
The routing table does not seem that difficult to me, and as a long-timer linux user and configurator I’m not too afraid in principle to do this – but I have no idea about HAOS, which tools it uses and whether I can simply have access to the router tables (be it via command line) or if I am restricted by some user-friendly GUI (read: web interface) that does not include my use case.
Why IPv6? My home network does speak IPv6 (and my ISP connection natively as well), but for simplicity I use IPv4 numbers for setting up the network, naming devices, subnets (well, only two in my case) etc. Should not be that different?
Why is wired easier than wifi? The HA Green having only one ethernet port, I thought I’d spare the ‘native’ eth for what HA does most (talking to devices), and Wifi would only host the interface, so it does not need to be available 100% of the time (but in fact it will, as HA will be at 10cms from the main home network router)

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(side note: I now discovered small devices with HAOS preinstalled and wifi connectivtiy, so maybe I’ll just settle for them instead of HA Green, rather than adding a wifi stick. At least I’ll know that the hardware will work with HAOS

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If you’re familiar with Linux you should have no problem installing HAOS on some old hardware you already own. Could you repurpose an old pc, laptop, or do you run a hypervisor or system where docker is installed (note if you go the docker container route you won’t get add-ons).

Regarding ipv6. This is what matter uses if you ever want to integrate matter devices into your home.

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7

If you use Fritzbox as your main router and have already segretated your “untrusted” devices to the Guest Network, then you will suffer. Source: I had the same setup, and was in your place.

The Fritz (depending on the models) have good hardware, but the software are not that much made to be that flexible, even when you can create firewall rules to for example block your IOT devices from the internet but allow internet time sync as soon as you get Home Assistant (HA) into you Guest Network, then there is not way for you to see it from your phone in your regular Network. This means that

:point_up: is impossible to do.

If you need intern (V)LAN connection, then you need to connect HA to both networks, the HA green will go out, you can use a mini pc and add an USB NIC (I have done that and works ok).

Other way could be to left your HA in the guest network and subscribe to NabuCasa to make your device available thru the internet (or configure this yourself which of course has security concerns if done bad), but then if the internet is gone, so is your access to HA until you change the wifi of your phone/computer.

Like I said, I was in your place, I checked possibilites, added a simple managed switch, then tried a second hand office switch, tried to make it work with the fritz an segmentation and it just do not work.

I almost ended in problems where I needed Layer 2 features that most switch do not have OR that needed a compatible router to work as expected (but I am not network professional).

At the end, I gave up and deviced to bite the bullet and migrate to a Unifi Network and now I have a better segmentation of my devices and control.

TL/DR:

Your options as I see them are:

  • You trust your IoT devices are “safe” (:see_no_evil:) and put everything on your main network.
  • You keep your segmentation and use HA thru “the internet”
  • You change your Network hardware.
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Fritz make good equipment, very flexible if configured correctly.

HomeAssistant thrives on a flat network, but can be configured to interoperate on an IOT VLAN if you carefully plan your network ahead of time. Examine what your data flow requirements are and plan accordingly.

Static IP Addressing can help considerably during the planning stage, and can make troubleshooting much easier, especially as your devices proliferate.

IPv6 is becoming essential as Matter/Thread devices become pervasive. Bring yourself into the 21st century!

Deploying your spare Fritz as a bridge/repeater/router, or just a switch?

Your HomeAssistant server should be hard wired as per recommendations. Avoid WiFi for the server.

Subscribing to NabuCasa should be for altruistic purposes, to support the HomeAssistant ecosystem. If you are doing it as a shortcut to bypass understanding fundamental networking principles, you are doing yourself a disservice, and you will struggle to get your described system working reliably.

Understand basic networking fundamentals is going to get you far further than relying on Gemini for educated guesses based on possible outdated hallucinations.

A Green is a simple way to implement HomeAssistant. You may come up against its limitations or not, depending on your requirements.