Inconsistent connection G4 PM-hub-DSL

Suddenly last week my G4 stopped connecting to the DSL modem (Cisco 675). The G4 is connected to a small hub which is connected to the modem and another larger hub for two other macs and some printers. Discovered with the help of Apple Care support that it works when connected directly to the modem. Some of the time, if I reconnect the cables, it will work through the hub but not consistenly. Always works when connected directly. When the G4 is not working through the hub, the cable from the hub can be connected to a Powerbook and the Powerbook connects with the internet. I have tried a new hub, new cables, consulted with Quest and my ISP.

Curious further, in that the arrangement worked for years.

Connected to the modem using TCP/IP, manually.

Now, I did have trouble with my OS X, and did put in a new OS using the Archive feature about a week before this happened.

Suggestions?

Len Schloff