Digimesh 2.4 TH -PRO

I need help to solve a problem with a digimesh network. This is our first installation. Devices are the XBP24CAUIT-001 Digimesh 2.4 TH -PRO with firmware version 9002

Our network contain 10 devices
1 master device (CE = Non routing coordinator) always on with node identifier NI = “MASTER”
2 repeaters (CE= standard router) always on
7 end nodes (CE=Non routing module) battery powered that wakeup every minute and send a short message to the master.

Indoor factory installation, max distance between devices is 10/15mt and master and repeaters antenna are in line of sight .

Network access procedure for a remote device, repeater or end node, is:
At first powerup, the device search the network
Device send the DN Discovery Node command with “MASTER” as parameter
Device wait for reply and if node not found repeat three times the request then change channel and restart the discovery node sequence on new channel.

When node MASTER is found device save the channel CH value and switch from search state to associate request state and send a request to MASTER node using the MAC obtained from DN command reply

MASTER reply to the end device association request with device configuration parameters, then end device change his network state to associate. In this state device and master exchange messages every minute in a definite 100ms slot
If echange messages fail for 5 consecutive minute link is lost and device return back to associate request state. Device try the network association sequence but If also this sequence fail, device go back to search network sequence and restart a search of “MASTER” device scanning all channels.

Our problem is this:
All device sometime lost the connection with the master , the end device come back to associate request state but if this procedure fail, the device return back to search channel and repeat the search network sequence scanning all channels. Randomly, sometime after one or two , sometime after 6 or more scan sequence failed, the DN command return the MAC of master device and device can reassociate to the network. The scanning sequence duration is 600s (510s scan + 90s waiting on channel 0x0C to allow local connection with XCTU). As a result the device sometime stay disconnected for 1hour or more

We are unable to explain why the radio link is ok for a few hours, then it drops with no apparent reason and we are unable to quickly restore the connection.
This behaviour is the same not only for battery powered devices that switch on/off and can be out of sync for other reasons., but also for repeater devices that are always on (powered with wall powersupply)

The scan procedure duration is 600s.
The N? parameter is 14,2s (rounded up to 0,1s)
The scanning procedure send DN message 3 times then change channel and resend 3 times the DN message. For the Pro version the available channels are 12
Total DN messages sent 3x12=36 mesages. If all messages fail 14,2sx36=511,2s after this time we set the module channel 0x0C and we wait for 90s. Total scan procedure time 511,2s+90s=601,2s Is EXACTLY the time measured with our debug procedure.

Our firmware set a software timeout with preset 10s+N?_value=24,2s If module not reply to DN message the scan procedure terminate after 24,2s and go back to reset the module. This never happen the module reply always to DN message but always at timeout.

Last info: between two successive scan sequence we reset the module pulling down the reset pin.

I hope someone help us and suggest where we need to investigate

This is not something that should be addressed on the Support forum but rather in a Support case. Please send an email to tech.support@digi.com with this information.