My question is if it is possible to have more than one controller in a Matter network and if it is possible, how would the connection be made?
It depends on exactly what you mean by a “matter network” but you can definitely have matter devices that were initially connected to one controller then be available in the app for a different controller. And you can definitely have more than one controller appear in the smartthings app.
(If you’re asking if you can take a thread network setup by one thread border router, and then create a larger mesh with a Thread network setup by a thread border router from a different brand, then that is not working on most platforms right now, but you don’t need to combine the thread networks just to use matter over thread Devices all in the same app and the same rules. )
Also, if you are asking if the matter controller from a different brand can be added to the app, only if it’s also a “matter bridge.“ See below.
So if we’re talking about adding, say, a smartplug to one matter controller, and then have it show up in the app for a different matter controller as well, there are three different ways that might happen.
1) multiple matter controllers of the same brand. This works fine on most platforms.
For example, some members have a V3 smartthings hub and one or more smartthings station hubs. Each of the hubs is a Matter controller, but they all show up in the smartthings app and as long as they are on the same smartthings “location” you can add a device to any of the hubs and use it in routines.
Or you might have several Apple HomePod mini’s, and then Apple TV 4 all in the Apple home app. Again, each of these is a Matter controller, and again, you can start by adding a matter device to any of them.
2) starting with a matter controller from one brand and adding the smartplug to the app for a matter controller of another brand.
This works well with almost all matter platforms. For example, many members use both Apple Home and SmartThings (I do myself). It’s definitely possible to begin by adding a matter over Wi-Fi or matter over thread device to an Apple HomePod mini and then use the Matter “multi admin “ feature to have the Apple Home app generate a QR code for the matter device, and then use that code to add the device to the smartthings app.
In this process, you’re not actually adding the first controller to the second controller’s app (the HomePod mini will not show up in the smartthings app) but the end device like a smartplug will show up in both apps.
Here’s the official support article on using multi admin with smartthings:
3) Matter Bridges.
“Matter Bridges” are not matter controllers, but they might apply to the question you’re asking.
Matter bridges work pretty much the way the Philips hue bridge worked before Matter.
You can add individual devices to the matter bridge using other protocols, typically zigbee or Bluetooth.
You can then add the matter bridge to a matter controller of another brand just like you would add any matter device, and the matter bridge will bring some of its end devices along with it so that they then show up in the app for the matter controller. Not all devices are all features, but it’s definitely useful.
So, like I said, that’s not a perfect match to your question, but it might apply in some specific situations.
For example, most of the Aqara hubs are now “matter bridges,” but not “matter controllers.” You can add the Aqara Contact Sensors to the aqara hub, and then add the aqara hub to the smartthings app through matter. In this case, the bridge itself will show up as a device in the smartthings app, along with some of its child devices.
So… At a network architecture level at the present time most platforms cannot combine thread networks into one mesh if that’s what you were asking.
But almost all matter controllers can use the “multi admin” feature to add an end device, like a smartplug, to their own app, and they can then generate a sharing code so that you can use a single smart plug in the apps from multiple matter controllers at the same time.
Did any of that answer the question or were you looking for something else?