Cable speed slow down using router or hub Problem

[catch36]

I have ATT broadband connection. I have notice recently a slow donw in download speed using either my linksys hub or linksys BEFSR41 router with a Motorola SB4200 cablem modem. Connecting the modem directly to the nic card immedicately solves the problem. I have tried changing the ehter net cable between the moden and or the hub and router but with the same effect. The download signal seem to be low at -15dBm. Could that be part of the problem?

[MadDoctor]

Can you borrow someone's hub or router? Maybe you have both (it happens) a bad hub and router.