Two cable modems, one router, connectivity problems

I would suggest that if you're paying for two lines that you get two physical lines into the house and get rid of the splitter.

Some things to ask yourself:

Does the Ambit have a status page you can check the power levels on ? If so, post your power levels.

If you swap the two ports on the splitter, does the problem move to the other port ?

What is the splitter type and model and what is the advertised DB drop on each leg (it may be written on the splitter or you may need to Google it) ?

As far as I know, this won't work. You need a separate feed into the house for each modem. A friend of mine had Comcast Internet service, and signed up for their phone service. A tech came out and installed the telephony modem with a splitter, just as you described. She asked me to come take a look, and I told her to call Comcast back and ask for a tech who knows more. He came out and shook his head at the first guy's work. Disconnected the old non-telephony modem, took out the splitter, and everything has worked since. John Jones, Detroit

What does it matter whether the signal is split at the house end of the drop, or the pole/pedestal end? Cable is a shared resource. Digital signals are differentiated by packet address, not by route.

It matters in that there is the DB drop of an extra splitter involved that shouldn't be there. The split at the pole is already accounted for - no need/want for any additional split in the house.

If the signal is so degraded that it won't tolerate a single CPE splitter, then the provider has some serious distribution problems.

Quite possible, but why would anyone try to run two modems off the same coax ? It's not done. That business line he has should have gotten a separate line from the pole. If there is a marginal signal, that should resolve the issue.

Your test (swapping the modem that's connected to the router) confirms the cable provider's conclusion that the modems aren't the problem. The problem is with your router, probably an error or incompatibility in the DHCP negotiation procedure.

The next time this happens, download the router's log and post the results, along with your question, to the alt.internet.wireless newsgroup.

Double-check any firewall settings on the problem computer. I once had a computer that had issues, and traced it to ZoneAlarm blocking a port connection to the router's address (typically 192.168.0.1.)

Thanks, Tom, I was wondering the exact same thing. It shouldn't matter at all where the split takes place.

I vote for Toms answer also, it doesn't matter that it's split. My cable connects to a 3 way splitter at the house. One for cable modem and 2 for TVs in separate rooms. All 3 drops work fine.

My incoming cable connects to an 8-way splitter outside the house. Seven legs go directly to various TV's throughout the house, but one leg connects to a 2-way splitter, with one of those legs going to the cable modem, and the other leg going to a 4-way splitter that then goes to a TV and 3 DVR's. It's far from ideal, but everything is stable and works fine. :)

That's fine if you have good signal levels, but the extra drop from the extra (unnecessary/unwanted splitter) could affect a marginal setup.

So does mine, but the cable modem is always put on the first splitter and there is only one split that the modem has to go through and that's always the first leg with the lowest drop on the splitter (and we still have no info on splitter type/model/drop etc).

Now throw another cable in for the business line (or other side) with no splitter and things should improve if there is a power problem.

Wow - that's pushing it. The modem should be on the first splitter. I would have used a 3-way splitter for the first one with lines going to

1) modem, 2) splitter to various TVs, 3) splitter to TV+DVRs. Obviously you would size the second two splitters as appropriate.

I figure the 8-way plus the 2-way are dropping around 12-14dB combined, but the modem is reporting +7 downstream and 41 upstream, and like I said it's been stable for several years now, so I haven't asked for any changes. At this point, if -I- made the changes without involving the cable company, my signal to the modem would be way too hot.

If ImLost had your line I doubt he would have posted. :)

Mine runs -4/50 with one 1->4 splitter to the modem and 2 TVs and a 1->8 on the other port for the rest of the stuff. I've got

Usually this is not done due to the problems with the billing systems not designed for more than one modem in an house, but it does happen. I've done it in college apartments, where the kids wanted separate accounts because they didn't trust their roommates would pay the bill on time, and it works just fine, as long as the splitter losses are taken into account.

Now, the frat house with 10 modems in it (and several wireless routers) was a different story...

When you pay the extra bucks for a business line you would expect to get a clean line from the pole and not put up with anything less.

I think we've come full circle. Regardless of whether it's business or residential, I would expect to get reliable service, and that has nothing to do with whether there is one line coming from the pole or two.

Of course it does. One method has an extra split in it - that has to lower reliability to some extent regardless of whether it works or not.