Hi @Pablo Porras ,
In this case, your client program is running using Local system or Network service. The account has been successfully identified on the SQL Server side, but you do not have the permission to log in to the SQL Server. The simplest solution is to add a "domain\machinename$" account to the login of SQL Server. Machinename is the machine name of the client.
For your case, adding domain\ServerSSRS1,domain\ServerSSRS2 in your logins.
This case may be helpful: login-failed-for-user-domain-machinename
If the reply is helped, please do "Accept Answer".
BR,
Mia