odogCable Centric Vendor BiasedPremium,VIPReviews:
reply to Madreag
Re: [AZ] Ultimate Tier, Consistent Slow Upload (~4mbps) 125Mbps is about the most you'll get on a 4x4 D3.0 modem.(SB6141 should help there)
What do you have hooked up to the modem? Try going straight to it with the computer. Also windows XP is a bit of a dog, make sure it is Vista or newer on Windows or Linux/OSX.