Tell me please, how to turn on asynchronous logging in Slack?
Slack logging is sending requests to Slack asynchronously but you might be getting limited by your default
System.Net.ServicePointManager.DefaultConnectionLimit. This can be changed by using
System.Net.ServicePointManager.DefaultConnectionLimit = 100 directly or via an app.config/web.config using the following example.
<add address="*" maxconnection="100"/>
Let me know if that sorts out the issue you're having.