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Problem： Modem restarts every 40 minutes or so, losing internet connection periodically. This is a SB5101 modem. Any potential fixes?
I called cox support, but all they see is that my modem is online and it was restarted, and they dont see any other issues. The modem reboot completes within 3 minutes, so it is not possible to call in when it is down.
Signal
Downstream
Frequency 849000000 Hz
Signal To Noise Ratio 36.4 dB
Power Level -9.5 dBmV
Upstream
Channel ID 2
Frequency 29600000 Hz
Power 45.7 dBmV
Log:
2014-03-19 22:43:37 6-Notice M573.0 Modem Is Shutting Down and Rebooting...
2014-03-19 22:43:37 3-Critical R004.0 Received Response to Broadcast Maintenance Request, But no Unicast Maintenance o
2014-03-19 22:43:04 3-Critical R005.0 Started Unicast Maintenance Ranging - No Response received - T3 time-out
2014-03-19 22:42:50 4-Error C401.0 DCC-ACK not received
2014-03-19 22:42:50 3-Critical R005.0 Started Unicast Maintenance Ranging - No Response received - T3 time-out
2014-03-19 22:42:50 4-Error C401.0 DCC-ACK not received
2014-03-19 22:42:49 3-Critical R005.0 Started Unicast Maintenance Ranging - No Response received - T3 time-out
2014-03-19 22:42:49 4-Error C401.0 DCC-ACK not received
1970-01-01 00:01:25 6-Notice I401.0 TLV-11 - unrecognized OID
1970-01-01 00:01:25 5-Warning D004.1 ToD request sent - No Response received
1970-01-01 00:01:18 5-Warning D003.0 DHCP WARNING - Non-critical field invalid in response ;CM-MAC=00:17:ee:60:a7:30;
1970-01-01 00:01:15 3-Critical D001.0 DHCP FAILED - Discover sent, no offer received;CM-MAC=00:17:ee:60:a7:30;CMTS-MAC
1970-01-01 00:00:09 6-Notice M571.1 Ethernet link up - ready to pass packets
2014-03-19 21:03:12 6-Notice M573.0 Modem Is Shutting Down and Rebooting...
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Have you tried to use the factory reset?
And, lol, those dates... 1970-01-01. What the fuuuuck?
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So, I searched your modem and found some strange answer to a very similar sounding problem. Check it:
+ Show Spoiler +So anyway, the 3rd tech who came to check everything out told me that if my upstream level goes above 50 dBmV, then the modem will reboot. Knowing that information I would watch the signal as my modem appeared to be crashing and sure enough the signal would suddenly jump over 50 and I would lose my internet. What appears to have been the problem is a barrel, whatever that is, that was attached to the wiring outside. The tech who fixed it (the 5th one to come out and the first who wasn't lazy and rushing to leave) said that he noticed the barrel was pretty old. He monitored the signal from the old one for a while and noticed that it was very jagged and jumping up and down, which would explain my sudden jump over 50 dBmV. He then replaced that barrel with a new one and monitored the signal from that for a while. The signal appeared to be straight so he told me to keep an eye on everything and to call him if the modem reboots again. Well, since he's left (which was about 18 hours ago) my upstream signal has not budged and is staying at a solid 42.7 dBmV. The downstream is barely moving and is sticking around 12.9-13.4 dBmV. Although the downstream is high he said I should not have problems unless that goes to 15 or above. So it appears as though my problem is solved. Now I have to deal with getting credits for my lack of internet over the past 2.5 months.
Get your ISP to send a technician and check the cable connection outside.
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The barrel is this part of the physical connection for reference:
+ Show Spoiler +
It's the center part of a cable/coax jack and used to connection two male-male cable pieces together. I don't know for sure since this is cable and I used to be an DSL tech, but 45dBm is quite high and a shit tonne of loss so that could very well be the problem. And a bad barrel could be a reason for that for sure, but not guaranteed the reason.
Either it's a bad modem that gets stuck in a firmware update and reboots or it's a problem with your cable line. Either way, it's something your ISP is going to have to fix most likely.
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What's a good power level or noice ratio? This is the first time I dig into a modem log, so I am not sure what range is good/bad. Thanks for the ideas. I'll check the box in the evening
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I can't say for sure since I wasn't a cable tech, but if it's anything similar to DSL (good chance it's not I'm sure), a Signal to Noise ratio higher than 15dB is a problem, and power loss higher than 30dB is a problem, but sometimes you can't do anything about the power loss of the cable office/terminal is far away. If the numbers are higher than those it usually indicates a physical problem with the line to your house (a short/grounded circuit/old connector/etc). Probably would need to ask a tech from your ISP the specifics on those numbers because they vary on the type of service (DSL/cable) and provider.
Ideally, all cable connections in your cable box and the coax cable from your modem to the wall should be wrench tight (can't unscrew them with your fingers), and only the cable jacks being used in your house should be connected to the coax splitter in the service box outside. Many cable providers require you to use a special tool to remove the screw to get into your cable box fyi, so you can't always check on your own. If you only have internet with your provider, there should only be a barrel connecting two coax lines outside (the line in from the street and the line that goes to the cable jack where your modem is connected).
If nothing inside your house has changed (like moving the modem), it's usually a problem in the cable box outside, a faulty modem, or something further down at the cable office. So unless you can get into the cable box and fix it by fiddling around, it's likely out of your hands.
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EPT![[image loading]](http://img.weiku.com//waterpicture/2011/11/9/2/F81_COAXIAL_RG6_SATELLITE_ADAPTER_BARREL_CONNECTOR_634658416176970360_1.jpg)
