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13 Messages

Wednesday, June 7th, 2023 10:03 AM

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Modem restarts at least 3 times per night

It's in the title. I have dealt with this for a while and only this past week have a tried to actually address it because it's becoming very frustrating. Typically i noticed this while gaming, my internet would drop randomly for a few seconds and then pick back up. It usually happened fast enough that I wouldn't be kicked from a game, but if i'm playing a game that involved aircraft, typically I'm in a flaming pile in the hillside by the time i reconnected. I dealt with this for a while because I haven't been gaming nearly as much since moving here, but It's become significant enough to go down this rabbit hole.

I upgraded from my Netgear CAX30 AX2700 Modem/router to 2 separate units. I now have (my 2nd) Arris S33, and a TP-link deco AXE5400 pro mesh system. The new setup was easy, i didnt hit any speedbumps. The network is solid. Fast forward to 01:03 AM on my first night off, my game lags, I look back and I see my modem flashing orange, its rebooting. Okay, annoying but bearable. 01:53 AM, reboot, and again just after, probably around 01:55 AM. I felt the modem and it was warm, I read reviews saying this thing typically runs warm, I put a fan next to it, not blowing on it, just enough to create airflow in that part of the room, its certainly not overheating. Another night and the same thing happens at the same exact same times.

I figure its a fluke, but I got it at best buy, lets just swap the modem to eliminate it as a variable. I have difficulty getting the 2nd s33 to talk to xfinity but after finally talking to a person after 2 hours attempting to get tech support, I finally get it online. As a bonus I somehow managed to schedule a real life tech to show up to my house the following day(yesterday). That night however, the modem reboots just like the other one did. I wake up the next day, ding dong its the tech, he shoots my wires, my connection is perfect. It's not the modem, its not the wires. Why is my modem resetting 3 times at the same time every night? Is this an ISP generated command to reset the modem? Who do I need to contact to stop this  disruption? 

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Visitor

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13 Messages

1 year ago

Hopefully my final update: A second field tech came out, took one look at the drop from the street and identified a grounding issue. Apparently our configuration was out of date 25 years ago (using a grounding rod rather than grounding to the house electrical). My signal was strong and clean, but it was susceptible to interference. I still have no idea what that interference could have been as my whole cable run had no high energy or fast moving systems anywhere adjacent. What ever it was, it's hopefully not my problem anymore.

He ran me a new drop from a different part of the line to the proper part of my house, grounded it to my power, installed a "pad"(?) to add resistance or something and force my modem to work a little harder(44ish dbmv now), which is apparently good in certain situations(? (I'm not the cable guy, I'm just trusting him on this)). Last night I used my same method and didn't identify any drops in signal during the predicted time windows. I got home this morning and my modem up time reflected the time I rebooted it before I left for work.

I wish I could say I picked out an explicit thing that was causing my clockwork connection issue, but I'm hoping this holds up and it doesn't come back when some hypothetical phantom EMI source kicks off. Thanks for all the help everyone and to anyone who reads this later, check your grounding, it matters more than I thought.

Accepted Solution

Problem Solver

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1.5K Messages

1 year ago

From the S33 manual:

Amber (solid) – power on/off status
Amber (flash) – firmware download is in progress
Green (blink) – downstream/upstream channel search (unlock status)
Green (solid) – online status in DOCSIS 3.0 mode
Blue (solid) – online status in DOCSIS 3.1 mode
Blue & Green (alternating flash) – error mode
Note: Detailed LED status information is available online in the SURFboard S33 user guide at the ARRIS support website, www.arris.com/selfhelp.


So, download firmware attempt.  Best you can do there is a factory reset to default in hopes of a clean state and hope it actually can do it.  Must be a pending Xfinity is trying to shove down the pipe.  
There isn't a way to control or block that on your end.  If it continues to fail, then I guess Arris #3 might be in your future if you can still exchange it.
I did also see there's a duplex mode change associated with the firmware update attempt, so that's probably what that is.  Interesting it was "ignored", but there is no technical spec on how the firmware download is supposed to work on that modem.  Firmware you can't update yourself is yet another problem.  Unfortunately, that's the way it is on Xfinity's network.

(edited)

Visitor

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13 Messages

@flatlander3​ I agree, it's awfully frustrating to be locked out of controlling a device in my own house. As I've tried the factory reset several times I'll just swap my modem out again. I'm not going to wait for them to sort the commanded push out on their side of the signal. Maybe another model won't have the same issue.

Problem Solver

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@user_4c3134​  Yes.  Yes it is frustrating.

3rd party firmware guy also has never screamed 'good security' to me either, so I always put a firewall in after the modem that runs software I can control, and can even compile in security fixes myself, or disable functions if there aren't any software library updates available to mitigate risks. 

Let a firewall do what firewalls do.  Let WiFi be Wifi.  Mesh network isn't a firewall appliance either, even though they claim to be.  You're still months behind on exploits if they even bother to spin a firmware to fix them at all.

Visitor

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13 Messages

Your comment about Arris #3 being in my future struck a cord. I decided to just get yet another modem, a netgear. I had it for the night got into a whole different can of worms where my tplink router blocked access to the netgear modem login page. However, at 0102 etc., it didn't disconnect. I had minor network hiccups but that's fine, I didn't get booted from my games.

I decided to simply revert to the initial modem/router, my CAX30 which I've had a history of issues with, but they're tolerable issues that I don't lose sleep over. I'm going to give you the accepted answer on this because for some reason, I can't get the arris S33v2 work for me- and another device is the answer for my problem. I really appreciate all of the diligence and effort you put into trying to help me solve this.

Problem Solver

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1.5K Messages

@user_4c3134​ It's too bad you are playing wack a mole with this, but on the plus side, you got your coax straightened out so whatever you end up using has a really good chance of working as properly as it can on their network.

...well....as long as xfinity doesn't "help you out" with a bad firmware push......

Problem Solver

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1.5K Messages

1 year ago

They can reset from the remote side, but that probably isn't happening.  You've got weak downstream power and your modem is pushing signal upstream a bit hard to get out.  It adjusts on the fly by itself.  You are on the edge in that current snapshot.  It also can vary over time, so it may be getting quite a bit worse sometimes. 

On my Netgear, when that upstream tries to shove much past 50dBmV uploads start flaking out.  Higher than that will cause a spontaneous reboot as it tries to save the front end.  Similarity on weak downstream, you'll start getting errors and will drop channels that then try to reconnect, and then rebond channels.  When that happens, you'll hit stalls as it goes down the error recovery path.  Your application also has to deal with a broken state active connection too when that happens.

If you want to look at it yourself, take a look here:  https://forums.xfinity.com/conversations/your-home-network/internet-troubleshooting-tips/602dae4ac5375f08cde52ea0 

You are looking for splitters (maybe even old ones not in use and still connected) and connector problems.  Ideally, you'd just have a clean, grounded run to your modem/gateway.  Some splitters are also forward path attenuators.  You'll some something like -7dB printed above the output.  It's a signal reduction.  If you can bypass it for a test, and take a look at the signals again, it might be useful information.  Trying to push signal through a splitter or corroded connector can be a problem too.  You can post the signal table again here if you try it.  

You can have xfinity come out too.  If it's a splitter or wiring problem in your house, you pay.  If it's upstream from you, you do not, but it might save you money to poke at it a bit yourself if you can get to the coax.  Trace it all the way to where it comes into the structure itself.  There can be a lot of goofy stuff installed over time. 

*I'd add, it may look just fine when xfinity looks at it, but signals do drift over time.  Maybe you've got an attenuator you don't need.

(edited)

Visitor

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13 Messages

@flatlander3​ I'll go ahead and do some experiments then, I took it at face value when the cable guy showed up, ran his test and said it was good. Same for the phone guy. But if my signal power is right on the edge, it makes sense why they would say it's technically "okay". I'll follow up on my next days off when I can verify wether this solves the issue.

Problem Solver

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1.5K Messages

Some installs have an amplifier too.  Small powered device for when your network infrastructure is bad or long runs.  If you have one, make sure it's plugged in.  It will have a wall wart/some means of getting power.  

I'd try running clean just for kicks though.  No nothing.  No splitter.  No amp.  See what happens.

Visitor

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13 Messages

@flatlander3​ I went ahead and connected straight from the street to my modem with one barrel connector, I don't use any other connections in the house. I noticed my SNR went up negligibly but my downstream and upstream power changed a bit, which I'm assuming is a good thing. I'll be sure to post whether I get a reset on my next nerd night.

Visitor

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13 Messages

My new router lets me remotely monitor network activity, so last night on a whim I decided to attempt to check at the exact time that it kept dropping out, i missed the 0103 window, but i checked at 0153 and was unsuccessful until 0157. I got home and checked my modem log, it showed an up time that reflected rebooting at that time. I'm fairly certain the issue is not signal strength and i still find it very weird that it's so predictable in when it cuts out. I just hooked it up to my UPS with my computer to hopefully block out any power fluctuations that could affect it. I'll post an update tomorrow using the same method to determine if it solves the issue.

**Also i used my AC socket tester to verify the power socket has a good ground and is configured properly

(edited)

Problem Solver

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1.5K Messages

@user_4c3134​ Yeah.  That looks really nice now.  Let us know.

Expert

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107.1K Messages

1 year ago

@user_4c3134 

FWIW. The signal values were now perfect at that snapshot in time. Good luck !

Visitor

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13 Messages

1 year ago

Just an update, powering it with the UPS didn't work. I have screenshots on my phone of the points when the internet was online, offline, online etc. I'd share them but it's just more pictures to verify I'm not crazy and that the internet drops at predictable times down to the minute even when not in use. I missed some screenshots because I was at work, but In summary:
0102 - Online
0104 - Offline
0105 - Online

0151 - Online
0152 - Offline
0153 - Offline
0154 - Online

0156 - Offline
0157 - Online

When I got home I checked my uptime it last rebooted at 01:56.
Its just wild to me that it's literally clockwork. I'm glad I have exact times documented now.
I have a field tech scheduled to show up again this afternoon, I'm going to try to escalate to a network engineer from there.

Problem Solver

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322 Messages

@user_4c3134 We would like to assist you further, if you could please send a direct message with your name, we can then look into this with you.

I no longer work for Comcast.

Problem Solver

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1.5K Messages

1 year ago

Well.  If they tell you nothing is wrong, and the signals look fine, there's a last ditch you can try for a test. 

Make note of the current firmware revision.  Then factory default the modem to wipe out any settings.  Make sure you do a physical power cycle (cord yank/wait 20 seconds) after it comes back up fully and rejoins the network.

If it loads a protected backup copy from flash, it might have a different firmware version.  Some devices do that.  Others just burn the new update directly.

If there's a nightly firmware push going on from Xfinity trying to update it, and that is bombing out, you want to give it as much free space to work with as you can, and start from the cleanest factory state as you can.

Look at the version tomorrow and see if the version changed.  

Is there another log file that shows you when it rebooted, what happened right before that, and the DHCP/DHCPv6 messages on boot?  It will probably say "time not established" on those messages when it happens since it's booting and not really connected yet (no NTP data at that point).  

Visitor

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13 Messages

1 year ago

Well, I'm absolutely fed up at this point. I wasn't on yesterday, but I was on tonight hoping to have a nice night of gaming with my newly reliable internet, and it dropped out. It seems as though it only happens on weekday mornings. 

Problem Solver

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1.5K Messages

1 year ago

OK, well.  When running out of ideas to try.  Is this your pro-mesh system? :  https://static.tp-link.com/upload/manual/2023/202305/20230508/1910013344_Archer%20AXE5400_UG_REV1.0.0.pdf 

Chapter 4 page 19.  Switch IPv6 to off just for kicks. Power cycle the modem, pull the power cord on pro-mesh.  Don't plug the pro-mesh back in until the modem up/down lights come back (booted and connected).  There's a race condition where you may get a junk class C address on pro-mesh if it connects to the modem before the modem is up all the way.  Now plug in pro-mesh.

Why?  DHCPv6 lease renews may be wrapped around the axle.  Or perhaps the router advertisements aren't working right with Xfinity, and there's a stall/lag there boning routing.  Also doesn't look like you've got much for options on that TP as far as IPv6 goes. 

See if it's stable then.  Sure.  Clients on it now will be IPv4 only, but this is just a test.

Visitor

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13 Messages

@flatlander3​ I can try that tonight, but last night I reset the modem and unplugged the router so it was just the modem plugged into the wall with the coax and power. It still reset at the next time window without the router being involved.

Visitor

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13 Messages

@flatlander3​ I just went and looked and apparently IPv6 wasn't enabled, I have no clue why. Is it possible that Xfinity could be trying to push some kind of information and having IPv6 disabled could cause it to get confused? I'm not sure how that interaction would be affected by having the router completely removed from the equation as I did last night.

Problem Solver

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1.5K Messages

1 year ago

When you say "reboot" are you just talking about the "timing sync fail" messages in the original error log you posted?? cause those aren't reboots.  Those are fleeting protocol errors.

Sure.  It's an error recovery, where it has to bond channels back together, and that takes time, can also stall an active state connection to something else, and whatever you are using for software has to recover from that, but it's not a modem reboot.

Are you picking up uncorrectable errors, especially on the ODFM PLC channel?

Visitor

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13 Messages

@flatlander3​ I'm not entirely sure what is going in inside the modem, but yes that error message does seem to correlate with the symptoms. Here's a video I took last night when I knew the next crash was going to happen. Prior to this I reset the modem properly by unplugging it for 10 seconds and left the router unplugged in order to isolate the issue. The modem comes back online a couple minutes later, and if the router is connected I would have connection again after that. 

(edited)

Visitor

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13 Messages

I forgot to mention: no, I have no uncorrectable errors showing up. I havent had any issues with those throughout the process

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