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C6300 Frequent short internet drops
I have a C6300 modem/router with Xfiinity cable internet. I have used this exact set-up for several years without any issues, but over the last few weeks my internet has been pretty bad. A...
Just wanted to give an update. I switched to a Motorola MB7621 (24x8 DOCSIS 3.0) modem and another router (an old TP Link that I borrowed) without changing/replacing anything in the coax line. That solved the problem immediately. My guess is the old C6300 modem-router hardware was failing.
do you have a copy of your event logs?
Your power is in spec but you have errors.
Problem with modems is that your power might be fine but have drop offs/issues with other channels. And the router can change channels that its using. So it might work fine for a while and then drop. thats where the logs are important.
This is a copy of the logs for the last few hours. While there are some events, none of the times correspond to the outages I experience.
| Description | Count | Last Occurrence | Target | Source |
| [admin login] from source 192.168.0.22 | 1 | Wednesday, 09 Mar 2022 21:56:55 | 0.0.0.0 | 192.168.0.22 |
| [DHCP IP: (192.168.0.26)] to MAC address xx:xx:xx:xx:xx:xx | 2 | Wednesday, 09 Mar 2022 21:53:55 | 0.0.0.0 | 0.0.0.0 |
| [DoS attack] ICMP Flood from 117.131.215.169 | 1 | Wednesday, 09 Mar 2022 21:44:20 | [my ip address] | 117.131.215.169 |
| [DoS attack] ICMP Flood from 192.172.226.141 | 1 | Wednesday, 09 Mar 2022 21:40:02 | [my ip address] | 192.172.226.141 |
| [WLAN access rejected: incorrect security] from MAC: xx:xx:xx:xx:xx:xx | 4 | Wednesday, 09 Mar 2022 21:13:07 | 0.0.0.0 | 0.0.0.0 |
| [DoS attack] ICMP Flood from 129.82.138.44 | 1 | Wednesday, 09 Mar 2022 20:30:44 | [my ip address] | 129.82.138.44 |
| [DoS attack] ICMP Flood from 13.244.144.10 | 1 | Wednesday, 09 Mar 2022 20:01:43 | [my ip address] | 13.244.144.10 |
| [DoS attack] ICMP Flood from 38.110.46.254 | 1 | Wednesday, 09 Mar 2022 19:43:39 | [my ip address] | 38.110.46.254 |
| [DoS attack] ICMP Flood from 58.48.53.181 | 1 | Wednesday, 09 Mar 2022 19:34:45 | [my ip address] | 58.48.53.181 |
| [admin login] from source 192.168.0.22 | 1 | Wednesday, 09 Mar 2022 19:29:22 | 0.0.0.0 | 192.168.0.22 |
thats the standard logs that show router side connections.
I want to see the modem logs. that'd be the event logs.Apologies for the mix up. This is the event log.
Time Priority Description Mar 10 2022 02:31:12 Critical (3) SYNC Timing Synchronization failure - Loss of Sync Mar 10 2022 02:28:26 Critical (3) No Ranging Response received - T3 time-out Mar 09 2022 17:19:19 Critical (3) SYNC Timing Synchronization failure - Loss of Sync Mar 09 2022 17:05:28 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1 Mar 09 2022 08:53:11 Critical (3) SYNC Timing Synchronization failure - Loss of Sync Mar 09 2022 08:50:19 Critical (3) No Ranging Response received - T3 time-out Mar 08 2022 04:09:09 Critical (3) SYNC Timing Synchronization failure - Loss of Sync Mar 08 2022 04:07:06 Critical (3) No Ranging Response received - T3 time-out Mar 07 2022 12:59:02 Critical (3) SYNC Timing Synchronization failure - Loss of Sync Mar 07 2022 12:52:19 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out Mar 05 2022 13:05:35 Critical (3) SYNC Timing Synchronization failure - Loss of Sync Mar 05 2022 13:01:18 Critical (3) No Ranging Response received - T3 time-out Mar 05 2022 12:54:43 Critical (3) SYNC Timing Synchronization failure - Loss of Sync Mar 05 2022 12:53:39 Critical (3) No Ranging Response received - T3 time-out Mar 04 2022 10:43:55 Critical (3) SYNC Timing Synchronization failure - Loss of Sync Mar 04 2022 10:29:52 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1 Time Not Established Critical (3) No Ranging Response received - T3 time-out You're getting line issues daily. Coupled with your errors, you need to check your line.
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, bad/old/cheap connectors, or corroded connections. Replace them if you do.
If you can, simply connect the modem right where the coax comes into the home. This prevents wiring in the home from being the issue. And some ISP’s charge if the wiring issue is in the home. So this helps prevent this.If that doesn't help, the isp needs to check the line.
Thanks for the reply. After I complained to Xfinity, they sent a technician to my house who replaced coax connectors and checked the signal in the basement where the cable comes in and also directly at my modem. He said the signal looked perfectly fine. I could try to have Xfinity come out again if you think there may be an issue with the line signal.
However, if it really is an issue with the cable connection, would that also affect the LAN connection to the router? Since I cannot ping the router from my laptop during the internet outages, I concluded something is also going wrong in my router and not (only) with the coax cable connection.
Problem with xfinity is if its something inside the home or the modem itself, they'll charge for home visits. The nicer techs will find a "bad" splitter outside the home but thats a gamble. And its not cheap to have them out.
so your options are
1. rent a modem from the isp. they're renting out docsis 3.1 devices and it might function better
2. upgrade the device. Again, maybe a docsis 3.1 would work better, maybe it wouldn't. the C6300 isn't the highest performing router or modem out there
3. if you're within your warranty period, you can try taking it up with netgear. sadly, if its not a hardware failure, it does cost to go through support.
Just wanted to give an update. I switched to a Motorola MB7621 (24x8 DOCSIS 3.0) modem and another router (an old TP Link that I borrowed) without changing/replacing anything in the coax line. That solved the problem immediately. My guess is the old C6300 modem-router hardware was failing.