My Big Ass Fans are connected to my guest wifi network. My Home Assistant Yellow is on my primary network (via ethernet). I am using eero routers.
With the BAF Alexa skill, BAF app and Google Home app, this is not a problem — the fans work fine. They seem to use an internet connection/cloud service to manage the fan.
However, the BAF HA integration requires a local network connection and requires me to type in the IP address of my fan. Since my fan is on a different subnet from HA, HA can’t connect to the fan.
Adding HA to my guest wifi (in addition to the ethernet) doesn’t seem to solve the problem, as HA gets a different subnet. (Wired/primary subnet: 192.7.x.x; guest wifi subnet: 192.11.x.x; guest wifi subnet for HA: 192.12.xx.)
As a workaround, I’ve added the fans to my main wifi network to get them running.
Can the BAF integration be extended to use a cloud service?
Is HA multihoming on both networks a viable solution? If so, how?
The short answer is no because whenever possible Home Assistant prefers and encourages local integrations that do not depend on the cloud. They are almost always more reliable and can never be taken away by a company shutting down their cloud service.
Eero are pretty basic routers and do not offer vlans, routing, and firewall configuration to let you isolate your fans from your main network. Generally speaking, using consumer network equipment, you really should use a single flat network. mDNS and many other devices and apps will simply not work otherwise.
Eero’s guest network is isolated from the main network on purpose. It’s not just a subnet or routing question, they also firewall those networks from each other.
I am however a little surprised adding HA to the guest wifi didn’t work. I am however unfamiliar with the details of the networks Eeros create and I don’t have Eeros to test with. Maybe someone else from the community can chime in.
Devices on the guest network are generally not forming a LAN. If your guest network is any good then guests are isolated from one another (some routers have a setting for it). The guest wifi is meant to give guests access to internet while not allowing them anything else to protect your own gear. It is not a separare IOT LAN.
You would not want malware on a guests device be able to spread itself to your fan.