CoAP port: port forwarding/triggering not needed?

While doing some maintenance on my WiFi router, I just realised, after all this time, that I have not explicitly defined any port forwarding/triggering on the CoAP port (UDP 5683).

So, how then does a Photon/Core connect to the Particle Cloud? Everything’s working fine, but I’m just wondering how the devices could use UDP 5683 as-is; I would have assumed that the router’s firewall would have blocked it by default.

fwiw I’m using a Linksys E2500 router with a PPPoE connection to my ISP.

Just a random guess, but I think it allows the connection since it’s going outwards, rather than inwards.


Thanks @Moors7, in retrospect it seemed like a silly question, but it made me look round a bit, and port triggering seems to be the answer as to how CoAP port could work from the get-go.

Was quite interesting (at least to me) to find out that most consumer routers actually allow outgoing data and port triggering, by default, on all ports!