Two Leaders in the same Thread Network - SDK 4.1

Question

Hello, 
 
 I am working on a project which requires 2 FTDs and 2 MTDs (Sensor and Actuator) in a Thread Network. 
 We are using nRF52840 dongle as FTDs and arduino nano sense BLE 33 as MTDs. 
 We manage to establish communication between these devices using UDP protocol. 
 The configuration is as follows : 
 Leader (Parent), Router and Two Childs. 
 The communication between the two childs and their parent is working fine. 
 When we try to establish a communication between the router and the leader (request/response), it works fine in the first instance, but after a while, the router becomes leader as well and the communication is lost. 
 Considering Thread Specification, a thread network cannot have more than one leader, we would like to know if it is a common bug and how we could fix it ? 
 Thank you in advance, I hope I've explained well the issue. 
 
 Kind Regards, 
 Houssam Slimani

slimhoussam · Accepted Answer

Hi Charlie, 
 
 Thank you so much for the prompt feedback. 
 Actually, we've found a workaround which makes the communication between router and leader more stable, now the router remains router permanently. 
 Indeed, we call the function otUdpSendDatagram(thread_ot_instance_get(), p_payload, &messageInfo) instead of otUdpSend(&sendSocket, p_payload, &messageInfo), so we don't use UDP sockets anymore, that's all. 
 I hope this solution could be valuable for the community in the future. 
 Thank you again. 
 
 Kind Regards, 
 Houssam Slimani