Seen different forums saying it works and doesn’t work.
I have the 3rd generation and and lots of walls so looking to add a few more STs in the area as all ST hubs will connect to the same wireless SSID for the backhaul to the cloud. A zigbee/zwave device could connect to either (hopefully the closest one).
Any issues here?
From the official support site:
But their use of controlled is weird. Does that mean from the app? From automations? Someone in the FaceBook group posted recently that they setup multiple V3 hubs and tings are working well, including automations. So maybe it only prevents local automations between hubs?
https://support.smartthings.com/hc/en-us/articles/115003226203-SmartThings-Hub-Miscellaneous-FAQ
That’s the miscellaneous hub FAQ. But the set up FAQ has the following verbiage:
https://support.smartthings.com/hc/en-us/articles/115002084806-How-to-add-a-SmartThings-Hub-
Note: It is not recommended to add a SmartThings Hub to a Location with an existing Hub.
During previous discussions some people reported that support had told them that while it was technically possible to set it up, they had discovered a number of problems with later operations, so that’s why it’s not recommended.
In particular, I’m pretty sure that anything using third-party Oauth, including voice assistants and Ifttt, won’t know what to do if you have multiple hubs.
Alternatively I wonder if it would cause issues if I had them on the same WiFi SSID but at least the hubs are far apart from each other? Like use you one for one area to handle devices and the other ones farther apart in another area to handle other devices. Or just put them on different SSIDs? My WIFI Access Points can broadcast multiple SSIDs.
I’ll try to talk to support to get their take on that too as I’m curious if the issue is that the Z-devices hear 2 different hubs and get confused.
No, it’s nothing to do with the local protocol, you could have multiple hubs in the same physical building and The individual devices still know which one they belong too. I’ve run as many as 4 zwave hubs in a quite small house at times. 
The issue has to do with the smartthings account structure in the cloud.
The issue will raise when you want to pair a device and you start the search. What do you expect which Hub will go into pair mode? Both? And they would reply the same time to a pairing request from a zigbee bulb?
No one can think that this could work well.
Look at this reply:
Sorry, but that makes no sense, and the response from support in another thread makes no sense either. 
It’s not the end device that starts a pairing request. It’s the hub. You have to start with the hub. That’s the “scanning for new devices“ step.Then You put the end device into pairing mode, and then it responds to which ever hub is sending out the scan.
As I said, I’ve had 4 z wave hubs operating in the same small house, no problem. (Two smartthings, one wink, one zipabox) They were all on different accounts, but end devices never got confused about which one they belonged to.
But more than that, there’s no problem with every unit in an apartment building having its own Z wave hub. Or even every room in a hotel, as the Wynn did in Las Vegas a few years ago.
Yes, there is a very small possibility that two people would be trying to add devices at the same time and they would accidentally connect an end device to the wrong hub, but it’s pretty rare and since the owner of that device would see that it hadn’t connected to their hub they will likely just reset it and try again.
So it’s just not a problem because it doesn’t work with the end device starting the process. The hub starts the process. All nearby Z wave devices hear that command. Only the end devices which are placed into pairing mode, typically by physical manipulation of that device, will respond.
As long as you don’t have one person in a household trying to add devices to, say, their ring alarm base station at the same time that another person in the house is trying to add devices to their smartthings hub, there’s no issue. Work with one hub at a time, and the devices will join to that hub. 
@JDRoberts, you are absolutely right. And the OP is correct too. It seems to be multiple Hubs can be assigned to the same account, and location. I’ve just noticed a setting in the new app, which allows you to select the Hub which you want to pair a device to. (I’ve never seen it before in the Classic app.)
And you are right about, that answer was again an incorrect “reset your hub” reply from support. But the setting might have not been there before the latest release.
The issue might would raise when you use the Classic app and you cannot select which Hub do you want to pair a device to. The scan for new devices starts on the “default” Hub, and not on the others in Classic. (Probably…)
Let me add here a picture in a few minutes from my phone…
In the +, Add Device, Scan menu on the top right, there is an option to select which Hub you want to use. I’ve never seen this before, but makes sense.
I believe the Classic app hasn’t got any feature like that, so multiple Hubs cannot be really handled for the same location.
so another +1 for the new app 
You can select which hub should be used via developer interface.
No one has mentioned this yet, but some z-wave device can have one lifeline node. Any additional hubs on the z-wave network will need to be configured using different association groups.
I suspect to make multiple hubs work, you would need to have only one of the hubs handle all local processing.
Thanks for the feedback all. I’m thinking it should work. Surprised this wasn’t working from the beginning.
I currently have a V1 hub. I want to get a V3 and slowly migrate all devices over. There are some devices that would need to stay on the V1 for a little more (1-2 years) while the rest can be remove and re-added all together at the moment. Is there any problem with this approach? Or should I just wait till I can migrate all devices at once?
If your time window is 1-2 years, then you can wait for the v4 or v5 Hub and the migration tool as well. 
Your idea about v3 is not bad. The new app supports multiple Hubs at the same location. You can select which one you want to use during pairing.
I see. My main concern is signal interference between hubs, especially for zigbee wave which could be affected by nearby wifi. I might’ve not been caught up with all the news but are you saying they do have plan for a migration tool? That’d be a great news for me.
No, I am not saying that. People are begging for it for ages. I meant to be sarcastic regarding the 1-2 year time window, what you have provided. But you never know what is coming.
Regarding the zigbee channel, I am not sure how the Hub chooses it initially, but I believe it would choose some with the least interference at start (randomly). But you can reset your new Hub until it gives you a channel what you want to have.
if this works as described above, using two hubs could actually be a good solution for access control. I want my kids to have RGB lamps in their rooms and be able to control their lights etc, but I don’t want them thinking its funny to turn on our bedroom lights at 3am - just because they can!
How do devices paired to separate hubs appear in the new app? Can they be in the same location and same room but on a different hub? That would be awesome if yes as would solve my ‘annoying children’ issue 
Also concur multiple z-wave hubs is not an issue. I have Ring, Smarrtthings and Zipato all running in my house at the moment.
I can’t answer the question on the multiple hubs, but the usual way community members solve the problem you are describing is by using one of the third-party dashboards, either action tiles or sharp tools. These allow you to custom select the devices that will appear on any one dashboard.
You can create custom dashboards with these so that, for example, one kid’s room only has the lights for that kid’s room. Their dashboard just doesn’t give them access to the lights in the other kids’ room or in your room.
Some people even get an inexpensive Wi-Fi no contract phone for these.
Or you can use an inexpensive android tablet.
Here’s a recent discussion thread. The topic title is a clickable link.
(one note: One of the major contributors to that thread, @tgauchat , sadly passed away late last year. If you have any questions about action tiles after looking at that thread, you can ask @625alex instead.)
The official support article still has the following note:
https://support.smartthings.com/hc/en-us/articles/115002084806-How-to-add-a-SmartThings-Hub-
Note: It is not recommended to add a SmartThings Hub to a Location with an existing Hub.
So they are still recommending only one hub per location, although technically it is possible to add more than one.
I remember having two caused some technical problems, but I don’t remember exactly what they were.
They are recommending one hub there. Elsewhere they are positively encouraging the use of more than one. Before anyone asks, I can’t remember where, but I am tempted to say it is the new app that suggests it now and again.
This seems to be one of the long running unresolved issues on the community.
I have two hubs on the same location. Apart from only one of them having been updated to the latest firmware, I haven’t noticed any issues. However having seen a webCoRE user with two hubs reporting that local HTTP requests were being made twice, I did wonder how hubActions worked with more than one hub.
