Motorola MB8600 showing connected but no internet

What do the modem's signal stats look like ? Try getting them here; http://192.168.0.1

The username is admin and the password is Motorola

Look under the "Status >>>> Connection" tab. 

Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.

Is this with a WiFi connection ? If so, for a test, does a computer / device that is hardwired directly to the SBG6700 gateway device with an ethernet cable have the same problem ?

With this test, we are trying to isolate this down to being either a WiFi-only problem or a problem with the general connection to the Comcast system which would of course affect both. It's a good first step of troubleshooting before proceeding any further. 

Thanks for the reply.  I'm unable to connect directly to the modem with the devices I have, but I'm reasonably certain it's not a Wifi issue:  I've had an Orbi network which has worked well for years, and this issue only started happening after I switched modems.  

Here's the requested info:

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected    1 Locked QAM256 41 675.0 1.4 41.3 0 0    2 Locked QAM256 13 495.0 1.1 41.8 0 0    3 Locked QAM256 14 507.0 0.7 41.8 0 0    4 Locked QAM256 15 513.0 0.5 41.8 0 0    5 Locked QAM256 16 519.0 0.5 41.8 0 0    6 Locked QAM256 17 525.0 0.5 41.8 0 0    7 Locked QAM256 18 531.0 0.5 41.8 0 0    8 Locked QAM256 19 543.0 0.0 41.7 0 0    9 Locked QAM256 20 549.0 -0.3 41.6 0 0    10 Locked QAM256 21 555.0 -0.5 41.6 0 0    11 Locked QAM256 22 561.0 -0.6 41.4 0 0    12 Locked QAM256 23 567.0 -0.4 41.6 0 0    13 Locked QAM256 24 573.0 -0.2 41.7 0 0    14 Locked QAM256 25 579.0 -0.4 41.7 0 0    15 Locked QAM256 26 585.0 -0.7 41.4 0 0    16 Locked QAM256 27 591.0 -1.4 41.1 0 0    17 Locked QAM256 28 597.0 -1.7 41.1 0 0    18 Locked QAM256 29 603.0 -0.8 41.3 0 0    19 Locked QAM256 30 609.0 -0.2 41.4 0 0    20 Locked QAM256 31 615.0 0.2 41.5 0 0    21 Locked QAM256 32 621.0 0.4 41.5 0 0    22 Locked QAM256 33 627.0 0.6 41.4 0 0    23 Locked QAM256 34 633.0 0.7 41.5 0 0    24 Locked QAM256 35 639.0 0.7 41.5 0 0    25 Locked QAM256 36 645.0 0.8 41.4 0 0    26 Locked QAM256 37 651.0 0.8 41.5 0 0    27 Locked QAM256 38 657.0 0.8 41.4 0 0    28 Locked QAM256 39 663.0 1.0 41.5 0 0    29 Locked QAM256 40 669.0 1.2 41.5 0 0    30 Locked QAM256 42 681.0 1.4 41.5 0 0    31 Locked QAM256 43 687.0 1.3 41.6 0 0    32 Locked QAM256 44 693.0 1.0 41.5 0 0    33 Locked OFDM PLC 159 722.0 2.0 41.5 737145 0

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)    1 Locked SC-QAM 1 5120 16.4 39.5    2 Locked SC-QAM 2 5120 22.8 40.0    3 Locked SC-QAM 3 5120 29.2 40.5    4 Locked SC-QAM 4 5120 35.6 41.0    5 Locked SC-QAM 5 1280 39.6 39.5

FYI I've lost connection three times today.  Each time the modem still appears to be connected, per the lights on the front.  

@zippityz 

Please redact all of the CM MAC and the CMTS MAC addresses in your error log entries for your privacy.  They are considered to be personal information. Personally identifying information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publically. It flagged your post as "Private".

Makes sense, hopefully this works:

The signal stats are o/k but the error log entries indicate that something is going on. Perhaps there is noise ingress into the line(s) /  an upstream channel-return path impairment somewhere.

There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !

Re-escalated...

I have the same issue. It has started after Comcast updated my modem's firmware. I had no issue before that. I would restart the modem once or twice a year, for 3 years, before receiving the update. Now I used to restart the modem when I leave in the morning and restart the modem after I come back :D No problem at all :D (this is how you eliminate the problem when Comcast doesn't do anything for you, except say that your internal cable is not a good quality one (FYI, I moved my modem and placed it near the window, and directly connected to the outside cable using the Comcast provided short cable, but they think it is a long cable) or rent a modem from us)