[Stealth]

i've got little to no experience with cable, but here's the deal:

My friend has a new house... big.  Cable comes into the house, goes up to the wiring closet on the second floor.  the coax then ENTERS a box, which splits it up into 12 or 13 pieces, which each go to the drops in every room in the house.  

The cable modem (linksys) and switch (one big linksys box, with the coax going into it, and then it has a wireless card, and 5 rj45 ports for hard wiring into it) are in his room

now everyone gets access to the network, no problem, all the computers connect to the wifi network with near perfect strength, but sometimes the internet will go down... sometimes for seconds, minutes, and yesterday: for the whole night and most of the morning.... for no apparently reason.  you'll load up a website, then click a link, and bam... it's down

i heard from someone that the cable modem should be hooked up on a split off the main coax wire coming in.

anyone else got any ideas/suggestions?
Thanks

[EtherShock]

You've just answered your own question.

That's right, it has to be split off the main coax before going into the house, otherwise you are splitting up the bandwith. A single cable connection split 12 ways isn't going to be much per connection. We have it split as I described first, and it works fine, with the exception of ocassional downtime. Hope this helps.

[mikhael]

Yes, but the house box almost certainly has a line-amp in it. That's the way most of these prewire systems in large houses are built.

However, the best thing to do is toss a two way splitter (3.5db loss to either output) and hang the cable modem off one side. In the case of an unbalanced spliter, hang the cable modem off the 3.5db leg, not the 7db legs.

Get a cable guy to come to your house and give you a read on the outlet your cable modem is connected to. It should be sitting between -10 and +10 dbMv. Really, it could be from -20 to +20, unless you're using a garbage cable modem.

Have the headend pull the stats off your cable modem. What's your signal to noise ratio? You can have all the signal strength in the world, but if half the juice travelling down that line is noise, you're going to have a ****ty connection.

Something else to consider is that cable modems are hub systems. Are your neighbors the sort that might be sucking down all the bandwidth? Everyone on your local node is splitting bandwidth with you, after all.

[mikhael]

While I'm thinking about it, what's your digital cable reception like? that'll give you some idea of what's going on with your cable modem (though TV is a little more forgiving: -30 to +30 dbMv is acceptable for most cable boxes). Remember though: in most cable plants, you're not actually in digital channels until you're up above 100 to 140. Have you checked your cable boxes diagnostics page? If you're on a digital channel and switch to channel 999 on many cable boxes, you'll get a diagnostics page that will tell you all sorts of nifty stuff, like S:N ratios, signal strength in db incoming AND outgoing (cable modems needs outgoing), what QAM you're on, etc.

And further, check the breakout box on the second floor. If there's a line-amp in there, it might have gone bad and only passing signal one way OR a splitter might have gone bad.

[Swamp_Thing]

Originally posted by Stealth
i heard from someone that the cable modem should be hooked up on a split off the main coax wire coming in.

That´s about it. When i installed cable, the technicians advized me to run a dedicated cable from the house entrance all the way to my modem, because getting the signal from one of the house´s outlets would weaken the signal. The end result would be a serious bandwith loss, due to packet loss on the connection.
Just like a TV signal, when your cable has too many terminations or is in bad condition, it looses strength, and you get signal loss. And that translates in slower efective connection, because data has to be sent more than once, since many data packets get lost in the way.

From where the main coaxial line enters your house, run a dedicated cable to your modem. Don´t share the cable with a TV. Grab the Cable TV signal from one of those outlets.

[Saturn2004]

uhh hmmm  this sounds like a  problem  my boss  had at the office  but the the only difference is that there was  only one  coaxial cable  connection coming in  from the   pole
anyways  it  is either the signal  strength or in my bosses'  take
you just need to hit the reset button on the modem get a pen  and look in the   back  of the modem  and hit the reset button
i know this will work  because it is how i  earned the  job  back then

[Stealth]

good try, but resetting the modem isn't really fixing the problem, it's a temporary workaroud :-/

mikhael and everyone else: thanks a lot for the help.  That could be why they also complain the internet is sooooooo slooooooow (it's almost like when i was on 56K.. takes 15 seconds to load yahoo.com)

As far as the neighbors sucking bandwidth, the house they live in is in a private neighborhood with a couple hundred feet between houses, and the network's also 64bit encrypted.

Does the main coax have to be split as it comes into the house?  Or can i split the cable going into the splitter on the second floor...

Mikhael, could i bother you for an exact list of what i should ask the cable guy when he comes to the house?

[Stealth]

TTT