# [SOLVED] Modem Constantly Reboots



## clg897

Hello everyone. I have an extremely frustrating problem on my hands right now. I have high speed cable internet service with Comcast and I currently have a Motorola SURFboard SB5101 cable modem, which is my own personal modem. I also have a Netgear Wireless-G WGR614 v9 router hooked up directly to the modem. I have had this setup since the beginning of August when I moved into my apartment for school.

Alright, so here's some information about my problem...

After the first couple of weeks my internet would just randomly die because the modem had somehow turned itself off and on. Within usually a minute I would have my internet up and running again. That would happen about once a day for probably a couple of weeks. It eventually stopped for months, with the exception of a random dropped connection here and there. Now, since probably two to three weeks before Christmas, my internet connection is dropping constantly. All of the lights on the modem just shut off and then it goes through its routine of trying to connect again. The only problem now is that it rarely connects again on its own. If it does, it takes forever. I have to unplug the modem, unscrew the cable wire from the back of the modem, plug the modem back in and wait until the power light is solid, then screw the cable wire back on. Once that is up and running there's a decent chance I'll just lose it again within a few minutes to an hour. This happens many, many times a day. Frustrated, I decided to go out and buy a new modem thinking the Motorola was just dying. I bought a Linksys CM100 cable modem and hooked that up hoping the problem would finally be solved. Well, the next day, guess what happened. Yeah, it did the same thing as the Motorola modem a few times and did that for the few days before I had Comcast look at everything. According to the tech who came to my apartment, my connection and everything is ridiculously strong. Right when he got there the modem died, but everything was coming through nice and strong so he was stumped and said he had never heard of anything like this. I had him setup the Motorola modem again, which is still having problems. The only thing I can think of is that the router may be causing problems, although I don't know what kind of affect routers have on a modem. I'm thinking of going out and buying a new router just to check it out, but does anyone have any idea what could possibly be happening? I would really appreciate any help I can get before I blow my modem up.

Sorry this is so long but I figured it would be best to let you know the entire story. Oh and by the way, my internet died a few times while I was typing this.


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## johnwill

*Re: Modem Constantly Reboots*

The new modem has the same issue. Perhaps some electrical flaw in the router is causing it.

Have you connected your computer directly to the modem and left the router out of the picture? Does that work?


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## clg897

*Re: Modem Constantly Reboots*

I haven't tried that yet but last night I actually updated the firmware of my router. I had tried to in the past but it never worked so I found a solution online for that. I don't think the modem has died since, although I haven't been using it much today to really pay attention. If it doesn't happen for a few days then I'll assume that solved the problem. If not, I'll try to unhook the router from the modem and see how that goes.

Thanks for your reply.


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## johnwill

*Re: Modem Constantly Reboots*

We'll be right here... :smile:


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## clg897

*Re: Modem Constantly Reboots*

Well, my modem decided to reset itself again today. I have been searching for any other information about this and I found out how to check the modem status and logs, which show that the modem has rebooted 11 times today, all but one of which were while I was at work. I currently have the modem disconnected from the router now and so far so good, although it's only been about 20 minutes.

My modem logs show that my connection is good, just as Comcast had told me. However, I notice in the logs that this message appears every time the modem reboots:



> 2010-01-11 16:15:08	3-Critical	R005.0	Started Unicast Maintenance Ranging - No Response received - T3 time-out
> 
> 2010-01-11 16:40:41	3-Critical	R004.0	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance o


Then right after that it says:



> 2010-01-11 16:40:41	6-Notice	M573.0	Modem Is Shutting Down and Rebooting...


Does anyone know what that maintenance message means?


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## johnwill

*Re: Modem Constantly Reboots*

That seems to indicate that the ISP is remotely commanding this. I suppose it could be a hacker playing around as well.

I'd contact Comcast, it's clear this is either the modem or the ISP connection.


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## clg897

*Re: Modem Constantly Reboots*

Alright, I scheduled another Comcast technician to come out and take a look at everything. I had tried disconnecting the modem from the router during the day while at work so that I could look at the logs when I got home and not interrupt my wireless connectivity. At first the modem didn't seem to reboot at all during the day. It also wouldn't reboot for a while after connecting back to the router again. Needless to say, this wasn't helping me figure anything out. Today, after having my modem reboot every few minutes for about two hours, I finally witnessed the modem reboot while disconnected from the router, so now at least I know that's definitely not the problem. 

I'll keep you guys updated so others in the future can figure this out without all of the drawn out frustration. I've searched all over and I have found that I am thankfully not the only one who seems to have had this problem but I have yet to see a single solution.


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## johnwill

*Re: Modem Constantly Reboots*

I think this is a Comcast issue, which is probably why it's so hard for people to fix.


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## clg897

*Re: Modem Constantly Reboots*

Alright, I'm back! I'm pretty sure the problem is finally fixed. After 5 Comcast technicians and experiencing the absolute worst customer service in the world, my modem is no longer rebooting. I wish I could tell you in detail everything that I went through. Needless to say, I'm writing a letter to the corporate office about my ordeal.

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.

I hope this will help others with this problem in the future. Thanks for all of your suggestions!


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## johnwill

*Re: Modem Constantly Reboots*

Sounds like my experiences when I used to have Comcast. :smile:


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## clg897

*Re: Modem Constantly Reboots*

Yeah, they are absolutely horrible. I can't even begin to fully explain what I have been through with them. Before this problem I was dealing with billing problems for months. One in the beginning of 2009 that lasted about 2.5 months and one in the middle of 2009 that took about 4 months to get them to fix, then now this problem that took another 2.5 months.

Anyway, I'll mark this case as solved after a few more days with no rebooting.


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## johnwill

*Re: Modem Constantly Reboots*

I hope you'll be able to do that. :smile:


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## PC_Guy76

Came across this post when I faced a similar problem. The "barrel" that is referred to here is actually a filter: SNLP-1GCW or similar unit. Can be installed outside in cable box or directly to modem. Takes less than a minute to complete.


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