Sigfox callback error

I’m trying to rewrite the pin value using the blynk API from the sigfox callback.
But it returns a bad request.

help me!

There are three different Blynk servers located around the world. Your project only exists on one of these.
To ensure that the Sigfox server resolves the correct server, you should replace with the IP address of the server where your project resides.
You can normally obtain the IP address by pinging from your home PC.

I’d also recommend using GET for all API calls, even pin updates.