CM500V and Synology RT2600ac: no internet

Question

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 · Answer

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.

plemans · Answer

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

pcb · Answer

&nbsp;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.&nbsp;&nbsp;I have posted this question on the Synology and Xfinity forums as well, no answers yet.&nbsp;&nbsp;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&nbsp; Comcast this morning to see if/how that changes anything.&nbsp;&nbsp;Settings are shown below, starting frequency is 0.&nbsp;&nbsp;Startup ProcedureProcedureStatusCommentAcquire Downstream Channel621000000 HzLockedConnectivity StateOKOperationalBoot StateOKOperationalSecurityEnabledBPI+IP Provisioning ModeHonor MDDhonorMdd(4)&nbsp;Downstream Bonded ChannelsChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectablesUncorrectables1LockedQAM25629621000000 Hz2.2 dBmV39.2 dB002LockedQAM2568489000000 Hz1.1 dBmV39.5 dB003LockedQAM25610507000000 Hz1 dBmV37.7 dB004LockedQAM25611513000000 Hz0.6 dBmV39 dB005LockedQAM25612519000000 Hz1.3 dBmV39.4 dB006LockedQAM25613525000000 Hz0.9 dBmV39.2 dB007LockedQAM25614531000000 Hz0.9 dBmV39 dB008LockedQAM25615537000000 Hz0.7 dBmV38.9 dB009LockedQAM25616543000000 Hz1 dBmV39 dB0010LockedQAM25617549000000 Hz1.4 dBmV39.2 dB0011LockedQAM25618555000000 Hz1.6 dBmV39.2 dB0012LockedQAM25619561000000 Hz2.1 dBmV39.5 dB0013LockedQAM25620567000000 Hz2.1 dBmV39.3 dB0014LockedQAM25622579000000 Hz2.7 dBmV39.8 dB0015LockedQAM25626603000000 Hz2.5 dBmV39.6 dB0016LockedQAM25627609000000 Hz3.1 dBmV39.6 dB00&nbsp;Upstream Bonded ChannelsChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower1LockedATDMA15120 Ksym/sec17300000 Hz40.8 dBmV2LockedATDMA25120 Ksym/sec23700000 Hz40.5 dBmV3LockedATDMA35120 Ksym/sec30300000 Hz40.5 dBmV4LockedATDMA45120 Ksym/sec36700000 Hz41 dBmV&nbsp;

plemans · Answer

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 · Answer

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.&nbsp;&nbsp;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). &nbsp;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.&nbsp;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.&nbsp;

Forum Discussion

CM500V and Synology RT2600ac: no internet

6 Replies