Your DSL-604 does, in fact have a system log. To access it it, youmust first access the router configuration page in InternetExplorer.
In Internet Explorer (or Safari on Mac OSX 10.4.1 and up),type the following into the address bar:http://192.168.0.1/
The default login information is: Username: adminPassword: admin
Click on the Maintenance folder, then click on EventLog.