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i'm trying to implement an observer resource on Arduino based on the following CoAP library. When the observed resource changes from 0 to 1 a message is sended to the CoAP client. The problem is that in the client side I receive the following error:

WARNING:coap:Received Type.ACK from <UDP6EndpointAddress [::ffff:192.168.2.121]:5683 with local address>, but could not match it to a running exchange.

First I thought that is a problem of my CoAP client. For that reason I used Copper CoAp client and the change from 0 to 1 is not reflected when observing the resource, so the problem is on the server side (Arduino CoAP Server). Looking to the coap_server.cpp the problem has to be inside 

void coapServer::notification(char *payload)

I wanted to have a look with Wireshark but I don't know what exactly what causes this problem. Any suggestions ?

gregory
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dani
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  • It's hard to tell with the data at hand. If you could listen in with Wireshark (while capturing, set the "display filter" line to coap to filter to the relevant parts), and then save and upload the displayed packages -- or simply "export packet dissections" to a plain text file and copy it over here. With that, it'd be easier to understand what's going on. – chrysn Jul 25 '19 at 20:37

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