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Multiple CoAP observe requests being sent to endpoint but not initiated by CoAP client

My client establishes an observation on /sensor/cto, this generally works, however, my endpoint continuously receives requests for that resource even though my client does not make the requests. Once a response is received to the observe request the client does not resend the observe request (unless we force it to).

The following endpoint logs show the request for /cto continuously being made, even though no client is making the request (that I know of, maybe SSN are testing it?). Note the requests for /9 and /ct are being made by my client, they are not observe requests though. This did not happen in the old starfish environment (hack day environment). This seems to be consistently approx. every 60 seconds


Re: Multiple CoAP observe requests being sent to endpoint.

I have tried with below settings and got the solution for our issue.

- I set the Max-age to 0, but the network still uses the default 60s (from rfc 7252 "If an origin server wishes to prevent caching, it MUST explicitly include a Max-Age Option with a value of zero seconds.”)  - I set the Max-age to 86400 and it seems to be honouring that, although I haven’t waited a day yet to test but I am at least not getting repeated requests now.

As I suspected, stopping the repeated /cto requests has fixed the issues I was seeing and things *seem* to working correctly now.