It shouldn't matter as long as it's only just your Modem being used at theat Jack? But I see their Setup guide shows to use it? http://kb.earthlink.net/case.asp?s=s...&article=28821
You leave the Modem On and you shut off the Computer. It's amazing that the Installer didn't give you any Info on the Setup ? Did you read this from above?
The Filters are needed,and do not have any effect on Speed. And you won't get kicked off if someone else is on the phone! Also, I don't know how your DSL is, but when I got SBC ( AT&T) DSL, there's a 10 Day Ramp up period. After that 10 day period,the Speed was pretty Stable. Here's a great...