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dimdem
join:2000-06-17
Norfolk, VA

dimdem

Member

Losing connectivity when connecting via router

My problem is that I'm regularly losing the ability to access the Internet. Some basic info:
1. Equipment: COX broadband, SB6141 modem, ASUS RT-N66W router
2. Symptom: I lose connectivity, but the lights on the modem don't change, so it doesn't look like the modem loses synch.
3. This has been happening on and off for over a year. It happened with an older SB modem and Linksys router, too; I actually got new equipment to try to resolve it. Sometimes it may happen once a week, but for the last couple of days it has been multiple times a day.
4. Cox sees nothing on their end.
5. Rebooting the modem solves it, temporarily. Rebooting the router doesn't.
6. So far, I can't reproduce it when I directly connect one computer to the modem. So it only happens when I'm going through the router. That's why I'm trying the networking forum.
7. Modem logs don't seem to show anything except the reboots that I perform.
8. I tried disabling NAT Acceleration, based on something I read online, but that didn't solve it.
9. I can't ping ISP addresses when this happens, so it doesn't seem to be a DNS issue.

Thanks in advance for any suggestions.
HELLFIRE
MVM
join:2009-11-25

HELLFIRE

MVM

Question, is the SB6141 in router mode (ie. handing out a 192.168.x.x address) or bridge mode (your
ASUS gets a nonRFC1918 address on its WAN interface?).
said by dimdem:

6. So far, I can't reproduce it when I directly connect one computer to the modem. So it only happens when I'm going through the router. That's why I'm trying the networking forum.

Did you try another router of the same make / model to see if the problem follows?

Did you try a different make / model of router?

Do you ever have the problem when you only have one computer directly connected to the SB6141?

Did you try testing/replacing the cabling between the SB6141 and whatever connects to it?

Does the SB6141 have any output about it's signal / power levels to COX?

If you have a friend / colleague also on COX, consider swapping equipment with them for a few days
and see if the exact same problem follows.

My 00000010bits

Regards

NormanS
I gave her time to steal my mind away
MVM
join:2001-02-14
San Jose, CA
TP-Link TD-8616
Asus RT-AC66U B1
Netgear FR114P

2 recommendations

NormanS

MVM

said by HELLFIRE:

Question, is the SB6141 in router mode (ie. handing out a 192.168.x.x address) or bridge mode (your
ASUS gets a nonRFC1918 address on its WAN interface?).

Eh? The Motorola 6141 is just a DOCSIS bridge; no native routing capability!

Hard Harry7
join:2010-10-19
Narragansett, RI

1 recommendation

Hard Harry7 to dimdem

Member

to dimdem
First, do you have normal Cox residential service? I assume DHCP? Second, do you notice if your public IP address changes when you reboot the modem?
said by dimdem:

7. Modem logs don't seem to show anything except the reboots that I perform

No T3/T4 errors or anything marked critical?
said by dimdem:

9. I can't ping ISP addresses when this happens,

Can you ping the modem at 192.168.100.1 when the problem occurs?

dimdem
join:2000-06-17
Norfolk, VA

dimdem

Member

said by Hard Harry7:

First, do you have normal Cox residential service? I assume DHCP? Second, do you notice if your public IP address changes when you reboot the modem?

I'll have to keep an eye on that; it's not something I've thought to check.
said by Hard Harry7:

No T3/T4 errors or anything marked critical?

In the log there is the occasional "No Ranging Response received - T3 time-out..." but those don't seem to correlate with the problem. In fact, the problem hasn't recurred in the last 24 hours, but I had one of those messages earlier today.
said by Hard Harry7:

Can you ping the modem at 192.168.100.1 when the problem occurs?

Pinging I've never tried, but sometimes I can and sometimes I can't pull the modem page up in the browser.
dimdem

dimdem to HELLFIRE

Member

to HELLFIRE
said by HELLFIRE:

Did you try another router of the same make / model to see if the problem follows?
Did you try a different make / model of router?
Do you ever have the problem when you only have one computer directly connected to the SB6141?
Did you try testing/replacing the cabling between the SB6141 and whatever connects to it?

I laid out what configurations I have and haven't tried in my post. The cabling is a good suggestion. I had one other cable handy and it turned out to be unusable. I'll get my hands on a good one and swap them out.