Siemens Speedstream 4100 problems

I have a Siemens Speedstream 4100 modem (ethernet connection) connected to a wireliess linksys router G2.4 broadcom. Very randomly the connection to the internet breaks off without any trigger. Sometimes if inactive for a while but it can be in a middle of a session also. When the connection breaks I have tried to disconnect the wireliess router and connect direct to the modem but still cannot revive the connection. Every time I have even swithced off computer & modem but to no avail. There is a little reset pin behind and even using that doesnt seem to help. The connection comes back after a while sometimes by repairing, sometmes just swithching off and trying after a couple of hours. The ISP technical support thinks it may be a modem problem, the modem supplier says it will cost a few hundred dollars to buy a new modem. The LINKSYS router seems to be fine and not contributing to the problem

We have a HP Windows XP desktop and Compaq XP/ Dell XP laptops which we use to connect and a firewall with zonealarm security suite.
rao

If the connection to the internet is being terminated then there obviously has to be an issue with the modem/router connected to the internet. Try resetting it back to factory defaults and setting it up again. If it still dissconnects for no apparent reason, get your telco to check youre line, an excessivly noisy, partially grounded (wet) or attenuated line may cause this. There may also be an issue with the termination equipment at the exchange.

If everything checks out with your telco, then replace your modem.

I hope this helps

Regards

Fred