I need some help to solve a mysterious network problem.
Here's our setup:
DSL Modem supplied by the phone company (SIEMENS SPEEDSTREAM 6520)
D-Link router (DI-604UP)
2 D-Link switches (DES-1024D and DSS-8+)
All devices connect to one of these two switches.
The Modem has been configured with all the DSL login credentials.
Users have sporadic internet connectivity. They can revive their connections by using the Windows networking "repair" function, but this only works briefly.
Rebooting the modem also works (briefly)
The LAN (managed by the D-Link router) seems to work fine in spite of the Internet connectivity issue.
If I connect a laptop directly to the modem, Internet connectivity is not a problem.
Modem IP range is 192.168.2.*, Router IP range is 192.168.0.*
Note: Since the modem has been configured with all the DSL login credentials. I have left the router with its default "Dynamic IP" setting for the WAN port. I have tried to configure it with the PPPOE credentials (as part of my troubleshooting), but I couldn't get that to work.
If you need any additional details, please don't hesitate to ask!
Many thanks for your input.