Netgear 7550 constantly drops connection when wired. Works fine on wireless.

My Netgear 7550 worked flawlessly for 7 months when I had my computer hardwired to the modem and the wireless feature disabled.  One day it started dropping connection and sometimes takes 10 minutes to reconnect.  When this happens the service light goes out and the broadband light flashes red.  When both lights come back on solid green the problem recurs as soon as I use the internet.

When I enable the wireless function and disconnect the wire the connection does not drop and the modem works normally.

I did not change any configuration settings, I have no new equipment (computer or otherwise), the location of all my equipment is the same, and the problem occurs whenever I try to connect using the wire regardless of time of day, or day of the week.

A service tech checked my line and said there is no problem.  That was before I realized I could use the wireless without a problem.

After a lengthy chat session with at&t today, the rep informed me that the problem is not with the modem but with my connection.  However, if the problem is with the connection it stands to reason that the problem would occur regardless of whether I was using the wire or the wireless.

Another factor to consider is that I am very far from the DSL point of service so my connection is very slow, but I do get consistent service, and as I mentioned, it was working fine for 7 months when wired.

Any suggestions?  Thanks.