Problem with slack integration

Hi I have some problem with Slack integration.
When I want to try slack configuration is always back this error:
Delivery: Post https://hooks.slack.com/services/id/id/id: dial tcp 52.84.197.158:443: connectex: No connection could be made because the target machine actively refused it.

I send request build by gogs in postman and everythink works.
It could by a proxy problem ?

I use:
Windows Serwer 2019,
MS SQL,
Gogs 0.11.86.0130

It definitely seems like a network error in your server.