I finally found the problem. Man, I'm so stupid. I forgot to add the instance name after the servername in the agent config  
				
			 
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				Quote from: Filipp Sudanov on May 12, 2020, 02:39:49 PM
This is error in a script of a Service Check object. 321 in the name of the script is the ID of that service check.
You'll find that service check, if you enter #321 into the filter in object tree. Check the script there.
HTTP/1.1 401 Unauthorized
Content-Length: 0
Server: Microsoft-HTTPAPI/2.0
WWW-Authenticate: NTLM
Date: Mon, 23 Mar 2020 10:51:21 GMT
Connection: close