Internet Dropouts HELP!!!

Is this with a WiFi connection ? If so, for a test, does a computer / device that is hardwired directly to the Asus router 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. 

There are two work computers hardlined, and two personal computers on wifi. They will all loose signal/lag, then recover at the same time. Sometimes its as short as a half second, but noticible enough to disturb a call, or see lag on runescape on the personal computer. Other times its as long as 10 - 15 seconds, and completely logs me out of runescape and my work pc.

O/k what do the modem's signal stats look like ? Try getting them here; http://192.168.100.1 

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.

Also. Are there any modem RF error log entries being shown ? If so, please post them as well in their entirety (copy and paste them, don't post a screenshot) but redact the CM MAC and the CMTS MAC addresses for your privacy. They are considered to be personal information. The posting of personally identifying information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publically.

  Cable Specification Version DOCSIS 3.1 
  
   Hardware Version V1.0 
  
   Software Version 8611-19.2.20

Connection
   Startup Sequence     
   Startup Step Status Comment 

  
   Acquire Downstream Channel 531000000 Hz Locked 
  
   Upstream Connection OK Operational 
  
   Boot State OK Operational 

  
   Configuration File OK  
  
   Security Enabled BPI+ 
  

   Connection Status     
   System Up Time 0 days 00h:25m:16s   
  
   Network Access Allowed   
  

   Downstream Bonded Channels    
  
   Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
   1 Locked QAM256 21 531.0 0.3 42.0 0 0
   2 Locked QAM256 1 399.0 1.9 43.0 0 0
   3 Locked QAM256 2 405.0 2.5 43.0 0 0
   4 Locked QAM256 3 411.0 2.0 42.8 0 0
   5 Locked QAM256 4 417.0 1.1 42.6 0 0
   6 Locked QAM256 5 423.0 0.5 42.5 0 0
   7 Locked QAM256 6 429.0 0.0 42.3 0 0
   8 Locked QAM256 7 435.0 -0.1 42.3 0 0
   9 Locked QAM256 8 441.0 0.2 42.4 0 0
   10 Locked QAM256 9 453.0 1.1 42.3 0 0
   11 Locked QAM256 10 459.0 1.4 42.4 0 0
   12 Locked QAM256 11 465.0 1.5 42.3 0 0
   13 Locked QAM256 12 471.0 1.1 42.3 0 0
   14 Locked QAM256 13 477.0 0.4 42.2 0 0
   15 Locked QAM256 14 483.0 -0.3 42.0 0 0
   16 Locked QAM256 15 489.0 -0.7 41.8 0 0
   17 Locked QAM256 16 495.0 -0.5 41.9 0 0
   18 Locked QAM256 17 507.0 0.4 42.0 0 0
   19 Locked QAM256 18 513.0 0.7 42.1 0 0
   20 Locked QAM256 19 519.0 0.7 42.1 0 0
   21 Locked QAM256 20 525.0 0.5 42.0 0 0
   22 Locked QAM256 22 537.0 0.0 41.9 0 0
   23 Locked QAM256 23 543.0 -0.2 41.8 0 0
   24 Locked QAM256 24 549.0 -0.4 41.7 0 0
   25 Locked QAM256 25 555.0 -0.5 41.6 0 0
   26 Locked QAM256 26 561.0 -0.5 41.6 0 0
   27 Locked QAM256 27 567.0 -0.5 41.6 0 0
   28 Locked QAM256 28 573.0 -0.3 41.7 0 0
   29 Locked QAM256 29 579.0 -0.1 41.6 0 0
   30 Locked QAM256 30 585.0 0.3 41.8 0 0
   31 Locked QAM256 31 591.0 0.4 41.8 0 0
   32 Locked QAM256 32 597.0 0.6 41.7 0 0
   33 Locked OFDM PLC 159 678.0 -3.8 41.3 32038879 0

   Upstream Bonded Channels    
  
   Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
   1 Locked SC-QAM 2 5120 16.4 42.3
   2 Locked SC-QAM 3 5120 22.8 42.3
   3 Locked SC-QAM 4 5120 29.2 41.8
   4 Locked SC-QAM 5 5120 35.6 41.8
   5 Locked SC-QAM 6 2560 40.4 44.3

Event Log
   Event Log    
  
    Time    Priority    Description 
    09:08:59
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:08:59
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-QOS=1.1;CM-VER=3.1;
    09:09:19
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:09:20
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-QOS=1.1;CM-VER=3.1;
    09:09:39
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:09:39
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-QOS=1.1;CM-VER=3.1;
    09:09:59
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:09:59
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-QOS=1.1;CM-VER=3.1;
    09:10:18
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-VER=3.1;
    09:10:19
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-QOS=1.1;CM-VER=3.1;
    09:14:34
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:45:14
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:45:20
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:46:05
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:46:05
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-QOS=1.1;CM-VER=3.1;
    09:46:26
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:46:26
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-QOS=1.1;CM-VER=3.1;
    09:46:45
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:46:45
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-QOS=1.1;CM-VER=3.1;
    09:47:05
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:47:05
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-QOS=1.1;CM-VER=3.1;
    09:47:25
Sun Jun 12 2022   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    09:47:25
Sun Jun 12 2022   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;;CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   No Ranging Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Notice (6)   Honoring MDD; IP provisioning mode = IPv6
    20:28:34
Tue Jun 14 2022   Notice (6)   DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-QOS=1.1;CM-VER=3.1;
    20:28:39
Tue Jun 14 2022   Warning (5)   REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-QOS=1.1;CM-VER=3.1;
    20:28:39
Tue Jun 14 2022   Warning (5)   RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;;CM-QOS=1.1;CM-VER=3.1;
    20:28:39
Tue Jun 14 2022   Warning (5)   Dynamic Range Window violation
    20:40:44
Tue Jun 14 2022   Critical (3)   SYNC Timing Synchronization failure - Loss of Sync;CM-QOS=1.1;CM-VER=3.1;
    20:40:46
Tue Jun 14 2022   Warning (5)   DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-QOS=1.1;CM-VER=3.1;


Let me know if you need anything else. I would love to be able to use my own modem, they came out and put a splitter on with a "test modem" running beside it. The test modem runs fine  hardlined, as well as runing through my router. Anyone have experience with this modem? Or know with the info above anything I need to fix?

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 values 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 (Cable Modem Termination System) to check for any real-time degradation and / or error reports, see your node / cable plant, and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !

No response, Technician came back out, told me signals were good and that it was my modem. went and got a brand new white xfi modem from the xfinity store. Internet is still dropping out. The new modem has 4 ethernet ports on the back, I have one personal computer and 2 work computers all plugged into it with brand new ethernet cords. They will all drop internet, then regain it at the exact same time. Sometimes for a few seconds, sometimes for 5min or longer. Kicker is, the entire time the xfi modem light stays solid white and xfinity website says my modem is online and functioning properly....... Any Ideas?

So was this ever resolved?  If so, what was the resolution?