Hello
I scrolled to many posts in this forum, however, I did not find a discussion for my thoughts. Sorry if I missed the post,
I would like to create a dedicated Wifi for Iot devices. I am not thinking about Vlans because I had strange network outages since I added HA plus a few esphome devices to my normal network.
So I think of this new Wifi to which I would connect the esphome and in future mqtt devices as well as the HA controller (nuc).
The HA controller would also be connected to the normal network via wired ethernet.
So the HA controller would have 2 different ip address addresses on the 2 interfaces. Routing between the networks would not be required.
I saw in the network configuration of the HA controller app that i can configure both interfaces already present on the HA controller hardware.
Are there any documents describing how to set up such a configuration?
I have an old TP-Link WA901ND wifi access point lying around - would that be sufficient to set up the iot wifi? It does provide DHCP service. Or do i need other equipment like a router or so?
Thank you for any information.
For a while I have wanted to do the same, to keep the organization simple, but have held off because my system has been rock solid (and there is no way anyone can get into the individual devices except for me as every single one of them on WiFi has an assigned IP addres as well as a very strong WiFi connection and a 30 digit password for access to their individual settings. 
I also use several VPN’s for outgoing internet access routing to non nine-eye countries on a rotating basis and with my configuration I can route individual devices to different VPN’s in different countries - or not (only for devices for which it makes sense - who care if people see what my nest thermosat is set to for example!) - so it is a fairly complex rearrangement for me to do - for not very much getting back in return (that’s not to say it isn’t worthwhile).
Have you set every single device in your network (except for random guests of course) to a specific assigned IP address, and then made sure the access points are not using overlapping channels (with each other or your neighbors)? Maybe the outages are due to IP conflicts or network traffic overloading your router - ?
I have a mesh network based on Netgear orbi, so I assume the inhouse wifi is managing channels well. I can see some neighbour networks, but with low signal strength.
Tha last time I had network errors , or lets say very bad performance, I saw this bad performance even accessing by qnap nas. So I think in that case I cannot blame my internet provider ( the line (fttc) is not very stable), it is an local network problem.
So after some browsing on the internet - using my phone not the house internet - I captured several minutes of network traffic with tcpdump I could not see anything strange, lots of ARP massages but I think this is normal in low traffic situations. However, I am not a network expert!
I then checked on the cisco switch and it reported no transmission errors.
So my current approach is to go without wifi ( and HA) for some time to see if errors occur. Then get the wifi for only “standard devices” and then maybe the esphome back.