MB8600 no owner access, blinking DL

Inflammatory?  Well perhaps others can see I am torqued and don't feel like your company should be in my credit card statement anymore.

um, don't see an actual question there, but.....

this page has default login info for MB8600 and instructions for doing a factory reset:

MB8600: No Internet, Slow or Intermittent Connection

No Zip21222 incorrect.  There are no factory reset settings once the modem has been upgraded by comcast.  It is impossible to access the web interface of the MB8600 due  to comcast upgrading it.  You cannot push the reset button to regain access.  They have coded it out in the upgrade.  Neither Motorola nor Comcast / Xfinity has any answers.  Do you see an answer from Xfinity here?  They are ignoring this question.  It exists in multiple threads. 

Same thing today 10 days later the modem is downloading something continually and rebooting it completely removing it or even trying the reset button does nothing to stop this behavior.  Remove all wiring and restart it after 5 minutes or 4 hours and immediately with no other device when it synchs up it continues blinking.  Nothing will stop this and no one at Xfinity will answer this question 10 days later!

OK it just stopped.  After hooking up a windows machine to use this useless forum.    Perhaps some xprt can explain.  I am willing to bet it begins this behavior again in number of minutes.  Xfinity any answers?  MSFT? [Edited: "Language"]

OK nothing to do with Mr Softy.   It just began blinking again!

Son of a gun....

https://forums.xfinity.com/conversations/your-home-network/xfinity-is-blocking-motorola-mb8600-modem-administratordiagnostics-screen/619d6ba376baea4aa19e7d02

the admin blocking has been going on for at least a year.

A new low, even for Xfinity.

Looks like time for a new modem. I have an Arris SB8200 and full access to it's admin functions.

HTH

Here I am with the same problem 6 months later comcast. Random service reboots of modem and cut outs  witht he blue DL light blinking non stop disconnected from the network.  What causes this?  It seems like something is looking for something here.  Cablehaunt 2.0 or what?

I have tried analyzing the problem.  I dont know what the [Edited: Language] it is thats wrong and comcast never helps but raises the price of my service no at 62$ when it started around 35 several years ago.

But the same problems continue. 

I am fed up with trying to solve this issue.  Whomever it was that directly messaged me above or asked for it I can only read my messages by logging in to the forum.  Comcast's  webpage on the account editting of details doesnt permit either linux based systems or just me cause they hate me from changing my email address from xxxxx@centurylink.net to my address used by my 2nd user account which is similar.    This [Edited: Language] will never get better it seems and I have had it with this.  The ironic thing is that the download blue light which seems to cause worse ping in a game and disconnects at times stops sometimes when I log in here,.m,  [Edited: Language]

They cant answer what the [Edited: Language] goes on on their own network.   I have tried analyzing this with ethereal known as wireshark and seen a lot of packets but nothing that explains why this is happening. 

The only good thing was I finally either tripped it in someway by directly connecting too the mb8600.   Either they changed the upgrade to allow the reset switch to work or this just tripped finally.

Not  thru the  rj45 4 port switch beyond it that has routing capabilities and denies many packets that are delivered by comcast's network that it sees as port scan attacks.  Perhaps I truly need a VPN.

But from what I see the service is unexplained why it does what it does and when it fails.

Here is some data from the modem.,  This is before I had comcast reboot the modem.

after the rebooted modem by comcast

this is the connection details:

The upstream power levels are out of spec. And the downstream power levels are on the low / weak side and it's out of spec on the OFDM channel. Some of the SNR's are out of spec as well. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, etc.

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.

Good luck with it !

dslforums has a thread on an earlier firmware upgrade on various MB86XX series cable modems removing the admin account interface and then later either deupgrading the status or altering the upgrade.  IDK. if they are related but it gives some info on an upgrade from January 23. 

https://www.dslreports.com/forum/r33571652-MB8600-Software-Version-8600-21-3-3

This may have little to do with mine but I think the behavior is odd and as stated it interferes with a particular browser based fps game, which maybe cloud based but offers multiple global areas served with different pings.

Hoping this doesn't happen in future with FPS Steam based games or installed games too.

Also I recall a lot of TLV packets and  TSLV or something ver 2.1 packets what I thought were Tivo related.  But We have no TIVO here. We have no RING and we have no WIFI and we have no IoT devices.

don't see how VPN would help with this issue when the modem is full of error connection messages.

Firmware isn't going to correct your poor connection quality. Try those tips and see if any apply.