Cox ISP: Gateway changes when removing router

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Sage2k

[H]ard|Gawd
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Mar 25, 2002
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Trying to troubleshoot a packet loss issue..

When my router is connected my gateway is 96.1...when i bypass router and connect computer straight to the modem my gateway is 108.1

I tried this several times with same result.

Either way I get packet loss so I guess it might be with my lines or my modem...

Just thought it was odd that the gateway changes...any ideas why Cox might be setup like that?


btw packetloss is around 2-5%...not enough to affect web browsing but basically makes Diablo 3 unplayable :(
 
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Can a bad modem cause up/down stream power level issues? or is that mainly a line/splitter only issue?
 
Sage2k said:
Just thought it was odd that the gateway changes...any ideas why Cox might be setup like that?
Click to expand...

They used a netblock from a different parent allocation to expand space in the DHCP pool. Nothing odd at all about it. A DHCP pool doesn't have to be contiguous.
 
Hmm i plugged into a different cable outlet and got much better up/down power levels, but still getting packetloss. I am pinging the gateway im connected to to test
 
Ok, spent an hour in the attic following lines...bypassed the splitter since we don't have cable tv service and have the modem directly connected. MUCH better power levels...and so far much less packet loss..
 
Downstream SnR: 38 dB
Downstream power level: -8 dbmV

Upstream power level: 51 dbmV

so they are all within spec now. packet loss is MUCH less. I still get the occasional packet loss though, its only noticeable when playing online games such as Diablo 3...
 
As I recall 51dbmV upstream is a bit high assuming they're using 64-qam, pretty sure it's supposed to be mid to upper 40's.
 
-Dragon- said:
As I recall 51dbmV upstream is a bit high assuming they're using 64-qam, pretty sure it's supposed to be mid to upper 40's.
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I believe you are correct. And that downstream is within the spec but well below what I would tolerate on an non-split line. How far are you from their tap?
 
so right now its probably a 50 foot cable coming from their tap outside going into a splitter that has IN/OUT/TAP...then it goes to my drop about another 30 feet from that. Before there was yet another splitter and my upstream was 57, so it dropped 6 just bypassing it. Should i go ahead and replace that IN/OUT/TAP splitter?
 
Downstream power level just changed to -12...im gonna replace that DC tap splitter and if it doesnt help I guess ill let the tech come and see if its on their end
 
Might need to consider getting your own bi-directional amp, helped my signal a ton.
 
Your 51 upstream power level is perfectly fine as long as it doesnt fluctuate too much. However if your downstream power level is bouncing -8 to -12, there's plant problems that need to be looked at. Could be trunk amp, line extender, your drop, etc.

Edit: go straight to the drop from your modem if possible. Bypassing all splitters
 
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I got a female coupler so i will try bypassing all splitters tomorrow. Then for good measure my friend gave me an amplifier to play with, at least use as a bandaid till tech gets here and sees if its on their end
 
An amp may not help or even hurt if it's only a downstream amp, it needs to be bidirectional.
 
Bypassed all splitters...NOT using the amp yet I am getting

Downstream power: -9
Downstream SNR: 39

Upstream power: 48

I'll see if downstream power fluctuates or not...

Btw I am using an OLD motorola surfboard...only docsis 1.x I think. Its like 8 years old. If I upgrade to a docsis 3.x would it be any better quality wise? My friend says they are able to use different signals and should be better....
 
The DOCSIS 3.0 modem will use multiple channels, therefore increasing the bandwidth capability significantly. Might help with reliability too. Have you already tried a different modem? An 8 year old modem has a good chance of being the culprit... Just saying.
 
An eight year old modem is begging to be upgraded. Go D3.0

I like the Motorola SB6121
 
I think im gonna upgrade the modem anyway just because its old, and hopefully the extra channels help...but since i bypassed all the splitters, quality is better but not perfect.

Upstream power is a rock solid 48 dBmV but downstream power will flucutate between -9 and -5 dBmV. It doesnt fluctuate quickly, but every so often when I check its different. Is this something thats mainly a line/telco issue or is it possible that an old modem will cause power fluctuations?
 
Sage2k said:
I think im gonna upgrade the modem anyway just because its old, and hopefully the extra channels help...but since i bypassed all the splitters, quality is better but not perfect.

Upstream power is a rock solid 48 dBmV but downstream power will flucutate between -9 and -5 dBmV. It doesnt fluctuate quickly, but every so often when I check its different. Is this something thats mainly a line/telco issue or is it possible that an old modem will cause power fluctuations?
Click to expand...

Thermals have a tendency to cause this with amps and lines. This time of year especially. Typically it isn't CPE related and doesnt always cause problems with your connection, but can indicate problems further up the line. It wouldnt hurt to have a new modem and would probably result in a more effective service call if the tech knows the equipement has already been swapped out.
 
I got a new docsis 3.0 modem...quality is better, but I still get an occasional attack of packetloss. I've bypassed all splitters and tried new hardware. The up/downstream levels are within spec though, so I hope if the tech comes to test their side he still finds something...

new downsteam power levels are -3 to -4 dbmv

upstream is now 47 dbmv
 
I have seen this exact problem caused by old modems on a few different occasions. Power levels can get all jacked up because the modem fried. The last one I replaced for this reason, I opened it up and there were two blown capacitors inside (I can't help but take broken things apart... lol).
 
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