Webhook seems to don't access internet

I'm switching from Api services to webhook and all the request give me a net_err.

I don't understand how it's possible, the url behind is the same that the one i used for the api services. I also entered the given ips in the ip filter but your ip never appear in all our logs (firewall included).

It seems that you never reach our server, and as it was working on api services, i think about some problems on your side.

Can you help me with that or is it possible to have more debug information than net_err in the panel ?