CM500V and Synology RT2600ac: no internet

[pcb]

Comcast/xfinity is my ISP. In August I replaced the comcast combo modem/router with a Netgear CM500V modem and a Synology RT2600ac router, with another Synology MR2200ac router downstream to extend the range. This has worked great for the last 3ish months, then this week the internet connection started to get intermittant, then dropped completely. 

When I connect a pc directly to the modem, the internet connection is great, with DL speeds around 300Mbps. But when I connect the router downstream, there is no internet connection. I tried both routers, and reset everything to factory defaults, with the same results: internet connection on the modem but it doesn't extend to the router. The router page indicates status of GOOD for both phone and router. 

Is this a modem setting, or something on the router? Thanks for any advice. Event log pasted below: 

Time	Priority	Description
Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:01:5c:76:42:6d;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:01:5c:76:42:6d;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Fri Dec 06 11:18:14 2019	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Fri Dec 06 11:18:05 2019	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:01:5c:76:42:6d;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:01:5c:76:42:6d;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=cc:40:d0:ea:e7:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;

[plemans]

do you have a screen snip of your modem connections page as well?

So it works fine if you have a pc connected to the modem but if you connect the router tot he modem, it doesn't work? 

Usually we tell people if a direct connection works great, then you move on to the next device in line that could be causing issues. 

Have you tried replacing cables? 

Are you booting up in the proper sequence?

shut both devices off, boot up modem and give it a couple minutes, then booting up the router? 

In terms of checking your router, you'd probably want to ask on the Synology forum as that'd be their device. 

[pcb]

Agreed that it would make sense that it is the router that is causing the issue, but I've tried two routers, both of which worked fine previously. I understand that Xfinity controls the settings on the modem, but I don't have a history of those settings to see if anything has changed. 

I have posted this question on the Synology and Xfinity forums as well, no answers yet. 

I have changed cables to make sure it isn't the cables. I have rebooted with the sequence you describe several times. Unless I figure this out, I'll probably go get a modem from  Comcast this morning to see if/how that changes anything. 

Settings are shown below, starting frequency is 0. 

Startup Procedure

Procedure Status Comment Acquire Downstream Channel 621000000 Hz Locked Connectivity State OK Operational Boot State OK Operational Security Enabled BPI+ IP Provisioning Mode Honor MDD honorMdd(4)

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables 1 Locked QAM256 29 621000000 Hz 2.2 dBmV 39.2 dB 0 0 2 Locked QAM256 8 489000000 Hz 1.1 dBmV 39.5 dB 0 0 3 Locked QAM256 10 507000000 Hz 1 dBmV 37.7 dB 0 0 4 Locked QAM256 11 513000000 Hz 0.6 dBmV 39 dB 0 0 5 Locked QAM256 12 519000000 Hz 1.3 dBmV 39.4 dB 0 0 6 Locked QAM256 13 525000000 Hz 0.9 dBmV 39.2 dB 0 0 7 Locked QAM256 14 531000000 Hz 0.9 dBmV 39 dB 0 0 8 Locked QAM256 15 537000000 Hz 0.7 dBmV 38.9 dB 0 0 9 Locked QAM256 16 543000000 Hz 1 dBmV 39 dB 0 0 10 Locked QAM256 17 549000000 Hz 1.4 dBmV 39.2 dB 0 0 11 Locked QAM256 18 555000000 Hz 1.6 dBmV 39.2 dB 0 0 12 Locked QAM256 19 561000000 Hz 2.1 dBmV 39.5 dB 0 0 13 Locked QAM256 20 567000000 Hz 2.1 dBmV 39.3 dB 0 0 14 Locked QAM256 22 579000000 Hz 2.7 dBmV 39.8 dB 0 0 15 Locked QAM256 26 603000000 Hz 2.5 dBmV 39.6 dB 0 0 16 Locked QAM256 27 609000000 Hz 3.1 dBmV 39.6 dB 0 0

Upstream Bonded Channels

Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power 1 Locked ATDMA 1 5120 Ksym/sec 17300000 Hz 40.8 dBmV 2 Locked ATDMA 2 5120 Ksym/sec 23700000 Hz 40.5 dBmV 3 Locked ATDMA 3 5120 Ksym/sec 30300000 Hz 40.5 dBmV 4 Locked ATDMA 4 5120 Ksym/sec 36700000 Hz 41 dBmV

[plemans]

t3 timeouts are fairly common. Not a big deal unless its happening quite requently. 

A couple things you can try.

1. remove any splitters, amplifiers, attenuators from your line.

2. prefereably just connect the modem directly where the coax lines enters the house. this prevents the wiring within your house from causing the issues.

3. Check your connections to make sure they're not loose/corroded. 

4. Check the cables for kinks. Replace them if there are.

These are some basic things you can do with your modem. Your signal looks great but its only a snap shot in time of when you opened the connections page. It also works when you plug your pc/laptop in. It makes me think its not the modem. But when it happens with more than 1 router.....anything is possible. 

Any chance you have a non-synology router you could try? 

[pcb]

I've replaced the cables multiple times just to rule it out. I can't have the modem right at the cable entrance, and because I'm consistently getting such a strong internet signal direct from the modem, I don't think it's a connection or signal issue. 

An update: I got a modem/router from Xfinity this morning. Both wired and wifi connections work fine. I changed the configuration on the Synology router so it is a WAP only, and it works fine, again solid internet connection via both wifi or ethernet (and wifi from Synology as WAP is set as unique, to clarify that network connection is coming from that router).

I then set the Xfinity modem/router up in bridge mode, so it acts more like a modem only. I put the Synology router back into router mode, and the internet connection is fine via ethernet/wifi connections through the Synology.

This sounds to me like the problem is with the Netgear modem, but I still don't understand what the problem is. I can live with this setup (keeping and using the Xfinity hardware), but not my first choice. 

[pcb]

Note that I contacted Synology tech support as well, and they agreed with the conclusion: there is some issue with the Netgear router. I've just slightly exceeded the 90 day warranty; will Netgear stand by this prodcut and issue a replacement? @netgear 

[plemans]

If it's a new device the warranty should be a year. But you'd need too go through support. This is the community forum.
Click mynetgear at the top. Register an account and then your device. From there you can contact support