Hello, Mr. Generation!
I want to report that I found the solution to my problem.
After checking the nginx error.log in /var/log/nginx/, it was possible to identify the message “[error] 3498 # 0: * 1 open ()” /usr/share/nginx/html/favicon.ico "failed 2: No such file or directory), client: 192.168.1.106, server: _, request: “GET /favicon.ico HTTP / 1.1”, then I accessed the /opt/zammad/public/ directory and identified that file was there.
With this, I used the command cp /opt/zammad/public/favicon.ico /usr/share/nginx/html/ and then changed the server_name to the server’s IP address, so it worked.
Thank you for taking the time to help me.
I apologize for my English, I do not speak the language and I have Google Translator.
Finally, Zammad is an interesting tool, I really enjoyed it.