nRF Mesh App changes network and app key, unable to reconnect to nodes

[domij]

We have a running sensor system with four sensors sending data to one central node (all nRF52840 Dev Kits). The nRF Mesh App was used to provision the nodes.

Now when trying to reconnect to the nodes on the nRF Mesh App, no nodes are found.

When checking on the app, the network and the application keys are randomly changed on all nodes and even in the app settings. Why?

No key update procedure was triggered from our side. Does the provisioner implemented on the app initiate key update procedures? Maybe when removing a node from the network?

Is there any way to connect to the nodes again? The network key cannot be changed in the app, because the app warns that the key is currently in use.

The IVI on the nodes is at 9, so not above the default 42 limit, where reconnecting to the network with the provisioner would not be possible anymore.

We are using the Mesh SDK 5.0 and the Android Mesh App 3.1.5.

[Joakim Jakobsen]

Hi. 

That sounds strange. 

I haven't seen a similar issue, so I have to forward this to our mobile developers so that they can take a look. 

Can you say anything about the timeframe in which you are trying to reconnect to the nodes? Is it 2 minutes or 4 days?

Br, 
Joakim

[domij]

Ok, thanks. It has been around 4 weeks after which I tried to reconnect to the nodes.

[Joakim Jakobsen]

Ok, then it might be related to inbuilt security features like key update procedures etc.

I'll check how this will impact the mobile app reconnecting and get back to you.

Br, 
Joakim

[domij]

Any news? I still think it has to do with the limit of 42 set by the mesh standard. Any way to change the IV index of the provisioner in the nRF mesh app? Does the provisiner handle the network beacon that is sent by the devices in the existing network, if it has the same net key assigned?