I have a customer who has had ongoing problems with their ADSL Internet connection. They have had to replace their modem/router at least three times in the last 6 months after storms have hit. The most recent time was yesterday. On two of those occasions, the NIC on the main board of one computer has also been taken out requiring the mainboard being replaced.
Yesterday when I left the site, the connection was up and everything appeared to be working as it should. This morning at some point things started playing up again. The modem (and Windows 7/8) shows as being connected to the Internet, but they can't open any webpage. They can ping a website and the ip address. If they put the IP address into the browser it won't open the page. It appears as though the connection is there, but going so slow that the browser times out before it loads any page.
This problem happened about a day after the modem was replaced three weeks ago, and it persisted for about two weeks. They have contacted Telstra (ISP) numerous times and had varying responses and attempted fixes, but nothing Telstra did seemed to make a difference. A Telstra tech visited the site and ran more tests but couldn't find any problems (but the connection had resumed prior to his arrival).
I'm not sure how to proceed. The ISP is claiming that there is nothing wrong with the connection.
Can anyone suggest some sort of troubleshooting process or set of tests that I can run?