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Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Attaached are my logs. Additional information includes that I indeed have a cable splitter in my box, but it connects it to only to the direct cable. Sooooo there is no need for the splitter. Does that harm anything or should I leave the splitter? Attached are my logs and info.

DOS Attack.pngDownstream Power.pngerror log.pngMain page.pngUpstream Power.png

Model: C7800|Nighthawk X4S-AC3200 WiFi Cable Modem Router
Message 1 of 20
plemans
Guru

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

remove any splitters, amplifiers, or signal attenuators from you coax line. 

Check the link for kinks, damage, loose/old/bad/cheap connectors and replace them if you do. 

Move the modem to right where the coax comes into the home and direct connect it. 

If after doing that the logs/connections still look the same, the ISP needs to check the line. 

Current setup: CM2000-> RBKE963B-> Trendnet TEG-S380-> GS716T-> pi-hole
1.4gig download/50mbps upload
We’re members of the public helping out on our own time.
Message 2 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Plemans,

I've crawled under the house and made sure the coax was intact and not damaged or freyed in any way. 

ISP just reported to me that they have no issues with my connection on their end. 

The ISP said to leave the splitter, even though it's not splitting anything, because my power levels are fine where they are.

 

Note:

-I bought this cable modem new in September 2021.

-Every morning I have to unplug and plug back in my cable modem about 10 times to get it to broadcast internet. Stays on for about 5 minutes then kicks off, but eventually sticks. I don't know if it is confirmation bias, but it seems like I lose interet during freezing temperatures.

-I performed a factory reset and my DHCP lease time went from 24 hours to 1 hour. (Personally spoke with ISP and they said they don't have control over that).

 

I'll have a line tech come out if it isn't resolved this week and the logs look the same.

 

 

Message 3 of 20
plemans
Guru

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

The reason to remove the splitter is because they can go bad and cause interference on your line. 

You're currently not locking the channels you should and you logs indicate a line issue connecting back to the ISP. 

So I'd take out anything in the line that could be causing issues. 

Current setup: CM2000-> RBKE963B-> Trendnet TEG-S380-> GS716T-> pi-hole
1.4gig download/50mbps upload
We’re members of the public helping out on our own time.
Message 4 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Plemans, I've removed the splitter, and it has effected the power levels in the following way:

This is post splitter removal:

 

Downstream Power NEW.pngUpstream Power NNEW.png

Message 5 of 20
plemans
Guru

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Power levels are a bit high but they're at least locking all the channels.

I'd be betting on a sketchy splitter. 

 

Is it running better? 

 

Current setup: CM2000-> RBKE963B-> Trendnet TEG-S380-> GS716T-> pi-hole
1.4gig download/50mbps upload
We’re members of the public helping out on our own time.
Message 6 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

I mean it is running fine. I'm paying for 200 mbps and according to speedtest I am currently getting 80mbps on 2.4ghz and 220mbps on the 5ghz band. I usually experience my disconnections in the morning. I wake up to no internet and keep resetting it until 9AM where it finally settles down and works consistently.

 

Should I reattach the splitter since my power levels are off now? Contact ISP? They'll probably know I tampered with it. I'll check the logs in the morning as well.

Message 7 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Also, are there any optimal settings that I need to be utilizing, or cutting off within my Netgear Genie settings? I have default settings.

Message 8 of 20
plemans
Guru

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.


@basstyler155 wrote:

I mean it is running fine. I'm paying for 200 mbps and according to speedtest I am currently getting 80mbps on 2.4ghz ---which is pretty good for 2.4ghz. its a slower network. -and 220mbps on the 5ghz band. ---perfect speed. I usually experience my disconnections in the morning.----cold can impact coaxial runs. when you already had errors/non-locked channels.  I wake up to no internet and keep resetting it until 9AM where it finally settles down and works consistently.---we'll have to see what happens in the morning. 

 

Should I reattach the splitter since my power levels are off now?----nope. Leave it off. I'd rather have it running a bit high but having everything locked than not. If we need to add one back in (we'll check the logs in the morning), I'd buy a new one Contact ISP?---Not right now. Seems to have locked the channels. Again, we can add one back in tomorrow after seeing if it stays half stable.  They'll probably know I tampered with it. ----they don't care if you take a splitter out of the line if its the one for your home. and if its inside the home and what was causing the issues, some will charge you a fee because the wiring inside the home is the responsibility of the home owner.  I'll check the logs in the morning as well.


 

Current setup: CM2000-> RBKE963B-> Trendnet TEG-S380-> GS716T-> pi-hole
1.4gig download/50mbps upload
We’re members of the public helping out on our own time.
Message 9 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

This morning was the same old routine. Interet was down when I woke up, and there were slightly freezing temperatures (30 degrees F). I kept unplugging and plugging the cable modem back in until a stable connection stuck. It took about an hour and a half. 

Here are my logs and information from this morning. A few DOS attacks and a lot of T3 timeouts starting at midnight, again (the time on the logs are 5 hours ahead of my real time zone). Power levels are still off, but the internet service is working fine after all the resetting. 

downstream power.pngEvent Log - Morning.pnglog.pngupstream power.png

 

 

Message 10 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

I would also like to show you a visual of the hardware. When I woke up and reset the cable modem, all the lights stayed on - but my phone/laptop would connect to the wifi but will state that there is "no internet access". Eventually, the lights went off to confirm no internet. 

 

Also, below are images of my cable box situation. The cable with the ORANGE tag attached to it is the only live coax cable that comes from the street. Everything else that you see has been severed or cut by a previous technician during a previous owner of the house. It is a birdsnest and I wish they would clean it up. Anyway, the following images depict the splitter that I removed from the ORANGE tag coax cable. The single live coax had two male ends, so I threw a spare adapter inbetween them to make a solid one-way connection without the splitter. To refresh, the splitter was the thing connecting the two male ends of the live ORANGE tag coax cable which is the only line that provides internet. This is the cable that eventually hooks into the back of my cable modem inside the house.

 

all lights.jpgcable one way vs splitter.jpglights off.jpgcable one way connected.jpg

Message 11 of 20
plemans
Guru

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Your logs are still indicating a line issues. 

what I'd try. 

1. buy a new 3x splitter. The old one might be fine but with it on, you weren't locking in your channels. maybe its got internal issues. So try a new splitter to drop your power levels back down a bit. To high of power can cause issues

2.  you're not showing "errors" in the cable connections page but if you just reset/rebooted it, it erases them. Next time there's issues, log into the cable connections page first and get the screen snip. 

3. When you reboot, sometimes the modem connects to a different range of channels and that might be why rebooting enough fixes the issue. I'm still better on the line having issues just based on the logs

Current setup: CM2000-> RBKE963B-> Trendnet TEG-S380-> GS716T-> pi-hole
1.4gig download/50mbps upload
We’re members of the public helping out on our own time.
Message 12 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

I've purchased a new splitter. Same brand and model. I couldn't find one local so it will be here sometime this weekend. I'll update you before Monday (if shipping is on target) and see if there is any improvements.

 

It didnt freeze last night, the low was around 36-40 degrees. With that being said, the internet was not down this morning. I reattached the old splitter yeseterday and it returned my power levels to normal. As of now, I have 31/32 locked channels, so it seems to be alternating between locking and unlocking.

Message 13 of 20
plemans
Guru

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

If the channels are lock and the signal looks good, it could have just had corrosion on the threads or a "jumped" connection on the shielding. I've seen that happen. 

Hope it stays working for you!

Current setup: CM2000-> RBKE963B-> Trendnet TEG-S380-> GS716T-> pi-hole
1.4gig download/50mbps upload
We’re members of the public helping out on our own time.
Message 14 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Update:

The new splitter was installed a couple of days ago. Internet stayed stable until the middle of the night last night when we hit freezing temps again (~31 degrees F).  

I woke up to no internet. It wasn't much of a hastle to get it back online; I only had to unplug and plug back in the router 1 time to secure stable connection. These are the logs/information after I reconnected this morning with the new splitter.

Downstream.pngevent log.pnglog.pngupstream.png

Message 15 of 20
plemans
Guru

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Your signal levels are spot on now. 

But the logs are indicating an issues connecting back. 

I'd be better on it something on the ISP's side  like the CMTS having issues in cold weather. 

Current setup: CM2000-> RBKE963B-> Trendnet TEG-S380-> GS716T-> pi-hole
1.4gig download/50mbps upload
We’re members of the public helping out on our own time.
Message 16 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Update:

A technician from my ISP came out to the house. They said my issues didn't sound like it was anything to do with their coax cables so he didn't even check them. All he did was replace the brand new 3-way splitter that I just bought with a 2-way splitter. My power levels are now different by a value of +-5 than the last time that we talked. 

 

The very next day the internet was out in the morning. I can't tell if it is terrbile customer service from my ISP, or if my cable modem is kicking the bucket 5 months in. It is obvious that my ISP is short handed and that they have low morale. I guess that is the norm? On the other hand, netgear won't help me without a $100+ dollar customer service contract and they won't take my modem back as a replacement since the "amber light isn't on".

Message 17 of 20
plemans
Guru

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

You're 5dbmv higher than you were? That's getting out of spec then because you were already at the upper end. 

do the logs look better? 

If that's all he did, he didn't do much. the should have checked the hub. 

And sadly, you're right on support. Unless its a hardware failure, it costs for support after the 90 days. 

And the lights are on and its working (for the most part) so the hardware hasn't failed. 

 

You're caught in the old rock<---you----->hardplace. 

Buy a new modem and see if it helps, rent from the isp to prove it isn't a modem issue, or pay the support contact and possible lost the $

Current setup: CM2000-> RBKE963B-> Trendnet TEG-S380-> GS716T-> pi-hole
1.4gig download/50mbps upload
We’re members of the public helping out on our own time.
Message 18 of 20
Bob_D
Tutor

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Been following along and I've had the same issues for years with the C7800.

I used to complain to my cable provider and finally after a couple years the tech they sent out listened to me and checked the cable from the connection at the house back to the street. All our services are all underground and the distribution box is across the street and down 2 houses. I have been telling every tech that showed up for 3 years that when we moved in the TV signal was noisy and poor signal quality (this was '98 and we still had dial-up internet). They always said the TV signal was good and would look no further. After a while (couple years) I noticed a correlation between the WX and the signal problems. Turns out every time it rained hard (>.5 inches) the signal would degrade significantly. I started including this observation in my complaints to my cable provider. Didn't impress enough to do any additional investigation at all.

 

But then after 3 years the tech that showed up used a TDR (I think that's what he called it) and found a bad section of UG cable 45 feet from the end of the cable. We located it and dug it up to find the outer jacket of the UG cable was damaged. It was in a flower bed and looked like it had been hit by a shovel. Must have happened before we lived there as we never did any digging in that flower bed. Anyway he did a cr@p repair to the jacket (didn't replace the cable) with some silicone tape then overwrapped with more tape. Signal improved and we didn't have any noticable problems for almost a year. 

 

Jump ahead and now our cable TV provider is also our ISP. In the beginning speeds offered were lower than today so maybe we didn't notice it right off. But the poor repair was now affecting internet service as well as TV. So I started with the reports to my ISP when the service would drop out. At this point I was renting the modem supplied by the ISP, a Motorola Surfboard but don't remember the model. Still the same issue with rainy WX and loss of service.

 

Jumping forward in time again a couple years and I now have turned in the ISP's modem and using the C7800 that I purchased. I bought the C7800 because I suspected the modem was the problem and the ISP said they did not have anything newer or better to provide me and that signal quality was fine as best they could determine remotely.

 

After a couple years of complaints again a knowledgabe tech (the one in a hundred I guess) showed up and listened to my recanting of the years of history of this problem and tested the cable from the house back to the distribution box. Every time it rained hard the cable would get saturated and the problem would not go away until we had a period of a week or more leater with no significant rain.

 

He found the same signal loss at the same location as the cr@p repair from years earlier. Dug it up again and found the repair had failed. He scheduled a cable replacement since the cable was buried and not in a conduit so he couldn't just pull a new cable from the distribution box to our house. Two weeks later contractor shows up and digs up everything and puts in new cable this time inside a conduit. Signal and internet speed is now better and matches what I am paying for. 

 

ISP/Cable Provider had nothing to say for their poor performance over the years. Didn't cost me anything for the replacement of the cable but then it shouldn't, outside wiring is theirs.

 

But the C7800 is another issue altogether, and not the ISPs fault. Well there is ONE issue that I have and will never put my self in this position again. I will never bundle my modem and router in the same device. Why? Because the ISP has control of the modem and in all the years I have owned the C7800 I have never received a firmware update. I can't update the firmware, that option does not even exist in the C7800. It is apparently from what my ISP tells me under their contorl even though I own the equipment. So years later and there is no update to the C7800 firmware. That does not seem likely.

 

I've had the C7800 for at leat 5 years now, and I lose connection all the time. When I look at the log I see DOS attacks and Echo Char Gen and UDP scans originating from outside my LAN.

 

I also notice that when the router reboots the times are often reported as 1969 and 1970. How does this make any sense. Why those dates so far back. How does a device manufactured in the 21st century even know about 1969 or 1970. What old piece of code in the firmware looks back that far to a time before the WWW existed and the internet  wasn't even known as the internet but consisted of a handful of computers running at Federal government agencies and a few universities on ARPANET.

 

My overall experience with the C7800 is it is one of the worst pieces of tech I have bought in the past 20 years. Support even within the provided support period was nothing to write home about. Wi-Fi side of the device is troublesome. Hardwired (ethernet) connections do better. Wi-Fi has issues tha tI have never been able to track down. Doesn't matter how far away or how many walls are between the end deivce and the router. I could be in the same room with line of sight access to the router and not make a connection on either band. Not being able to update the firmware factors in heavily for me. I don't like nor should I be at the mercy of the ISP for firmware updates. I understand my ISP's concerns and why they want control of that aspect of the hardware (the modem), but that also blocks me from updating the router side of the device.

Model: C7800|Nighthawk X4S-AC3200 WiFi Cable Modem Router
Message 19 of 20

Re: Nighthawk C7800 drops connection, has DOS Attacks, and 8/32 locked channels.

Plemans and Bob,

I wanted to provide an update after all of this time. Obviously we are in the month of May where freezing temperatures have subsided.

I have NOT had a SINGLE (not one) connection drop since February when the last time we hit freezing temperatures over night.

I don't see any firmware updates since my new device isn't supported for that anymore (eyeroll), because of this, I have to believe that there is water in the coax that freezes and interrupts connection. I've checked everything that could have been at fault.

 

I've explained this to my ISP but they will not replace the coax outside of the house because there is no way to test if there is actually water in the line or not. I do not want to buy a 100ft cable when they replace it for free if there is something wrong with it. I love internet, but hate ISP's. Thank you both for your expertise. 

Message 20 of 20
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