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CM1150V Upstream Channel Problem with Xfinity
I purchased a CM1150V to replace an Xfinity (Arris) XB6. The XB6 had been in place, running in bridge mode, for 2 months. It showed (4) upstream channels with good power levels, (31+OFDM) downstream channels with all power levels between 0 and -2, SNR all between 38-39, and 0 correctables/uncorrectables. Upload/download speeds exceeded my plan rating by 20%.
I disconnected the XB6, connected the CM1150V, and powered it up. On the initial power up, it appeared to get a firmware update shortly after going online (alternating up/down leds, then reboot). Firmware is reported as V2.02.03. Activation through Xfinity's portal went smoothly, with both voice and data working. As with the XB6, the downstream shows 31+OFDM, good power levels and SNR.
The only problem... The CM1150V will only bond (2) upstream channels. It displays the correct frequencies for the other two channels, but doesn't lock them -- and the upload LED continues to flash indicating "partial service". Tried a couple power cycles, then a factory reset. It still would only lock (2) of the (4) upstream channels.
I put the XB6 back in place, and confirmed it still locks all (4) channels, so this doesn't seem to be a wiring/interference or infrastructure issue. I put the CM1150V back in place, and it still only locks (2) channels.
Here's what the XB6 reported for upstream channels:
And here is what the CM1150V reports:
Xfinity says the CM1150V is provisioned correctly, and should lock all (4) channels. The XB6 locks all (4), so it doesn't seem to be a wiring, interference, or headend problem.
Any ideas? Do I have a bad CM1150V?
An Xfinity tech was out today. He found a noise block filter at the pole. No idea when or why it was installed. That was blocking the two lower frequency channels.
A noise block filter had previously been ruled out, because the Xfinity-supplied Arris XB6 was reporting all (4) channels locked. So I now question the veracity of the Arris XB6 status page. All other modems tested (CM1150V, Arris TM722G, Arris SBV3202) were unable to lock the channels with that filter in place. So I don't think the Arris XB6 was actually locking those channels either, even though it said it was.
Once the tech removed the noise block filter at the pole, the CM1150V immediately locked all (4) channels. The constant T3/T4 errors are gone as well. No problems with the CM1150V, the upstream issue was all from a previous Xfinity/Comcast tech installing that noise block filter at the tap.
Thanks to vkdelta for help and supporting information, which helped me explain/prove the problem to Xfinity so they would come fix it!
33 Replies
1. There might have been an outage on comcast plant. Please reset to confirm if you have 2 or 4 US channels
2. Have you changed anything on your side? such as coax cable? or connector?
vkdelta wrote:
1. There might have been an outage on comcast plant. Please reset to confirm if you have 2 or 4 US channels
2. Have you changed anything on your side? such as coax cable? or connector?
Hello vkdelta ,
Thank you for responding.
1a. I have restarted the CM1150V multiple times over a 48hr period. Have also factory reset it. The CM1150V only locks (2) US channels.
1b. Reconnecting the Arris XB6 to same connection, it locks all (4) US channels just as it did before. Reconnecting the CM1150V to same connection, it is only locking (2) US channels.
2a. Drop, cable ends, moca filter, and single splitter have all been checked and swapped out. All quality materials and parts as per Xfinity. Again, the Arris XB6 locks all (4) US Channels on the same cable and connector. The CM1150V is only locking (2) US channels on the same cable and connector.
2b. All downstream signal levels are good, between 0 and -3 dBmV, with SNR between 38 and 39. The two US channels that lock have upstream power between 40 and 42 dBmV. These US and DS levels seem to indicate good cable and connections.
2c. The Arris XB6 locks all (4) channels. Disconnect it, connect CM1150V, and CM1150V only locks (2) channels. Disconnect the CM1150V and reconnect XB6, it again locks (4) channels. Can do this over-and-over, the problem is NOT intermittent. The XB6 always gets (4) US channels, the CM1150V always gets (2). It lists the proper frequency for the other (2), but does not lock. This is on EXACT SAME COAX and CONNECTORS.
2d. Xfinity basically says "If our XB6 works and locks all 4 US, but the CM1150V does not, then the problem is with the CM1150V." I see their logic, but find it difficult to believe that a defect in a brand new CM1150V would only affect locking (2) US and nothing else.
Still having the same problem. I procured a second CM1150V, and it behaves exactly the same way -- it only locks 2 US channels. Yet I can connect the Arris XB6 and it locks 4 US channels. This is in the same location, on same coax and connector. The XB6 locks 4 US, but the CM1150V only locks 2 US.
The CM1150V units (both of them) also have a constant stream of T3/T4 timeouts, roughly every 30 seconds. The Arris XB6 has an occassional T3/T4, perhaps a couple per day. But the CM1150V continuously posts T3/T4 errors about every 30 seconds, they never stop.
What would cause the CM1150V units (both of them) to only lock 2 US channels and get constant T3/T4 errors, while the Arris XB6 is able to lock 4 US and not get T3/T4 errors?
Not sure if this is related to this post, or if I need to start a new one.
Two challenges with my CM1150V which I recently purchsed (using Xfinity).
The upstream light is always flashing green. Never solid green like all other lights.
Also, my router is plugged into Ethernet Port 1. Works.
When I plug anything else (ie PC) into ethernet ports 2,3,4 nothing happens. I should just get direct hardwired internet to my PC? Correct?
So why do the other 3 ethernet ports not work.
Please advise.
FunBucks wrote:
The upstream light is always flashing green. Never solid green like all other lights.
I am curious about this as well. When I was only getting 2 of the 4 upstream channels, the GUI said "(partial service)" above the channel list AND the upstream light was flashing to indicate "partial service". Now that I'm getting all 4 upstream channels, the "(partial service)" text is gone from the GUI -- but the upstream light is still flashing. Have rebooted and factory reset, but the LED is still flashing. Hopefully someone from Netgear can answer that for both of us.
FunBucks wrote:
Also, my router is plugged into Ethernet Port 1. Works. When I plug anything else (ie PC) into ethernet ports 2,3,4 nothing happens. I should just get direct hardwired internet to my PC? Correct? So why do the other 3 ethernet ports not work.
The CM1150V is a modem, not a gateway or router, so it has no routing capability. You'll need to connect your router to the modem, and your other devices to the router. The additional ethernet ports are for the "port aggregation" feature, which allows (if you have latest firmware, a plan with sufficient speed to need it, and a modem that supports it) a multi-gigabyte connection between the modem and the router.
customer>>
The upstream light is always flashing green. Never solid green like all other lights. -
response>>
This is because of partial service on upstream. if you fix the coax/line/plant issues and all 4 upstreams are locked.
customer>>
Also, my router is plugged into Ethernet Port 1. Works.
When I plug anything else (ie PC) into ethernet ports 2,3,4 nothing happens. I should just get direct hardwired internet to my PC? Correct?
So why do the other 3 ethernet ports not work.
response>>
Port 2,3,4 will only work if you have Multiple IP service package for different IPs. Some ISPs offer it, not all though.
Port 1,2 will work together if you enable LAG and have LAG-capable router.
I can't tell if my problem is the same or not. Just activiated my cm1150v. The problem I am having is that I have an ethernet cable run right from the modem to my computer (from port 2), and then an ethernet cable running to my router out of port 1 as instructed in the manual. However, when I have them both plugged in at same time, only 1 works at a time; meaning only 1 can access the internet it seems. So, If unplug my laptop, the router will start connecting to the internet. If I unplug the router, the comptuer will start working. Obvioulsy I have rebooted everything numerous times. My previous Arris never had a problem once
schillit wrote:
I can't tell if my problem is the same or not. Just activiated my cm1150v. The problem I am having is that I have an ethernet cable run right from the modem to my computer (from port 2), and then an ethernet cable running to my router out of port 1 as instructed in the manual. However, when I have them both plugged in at same time, only 1 works at a time; meaning only 1 can access the internet it seems. So, If unplug my laptop, the router will start connecting to the internet. If I unplug the router, the comptuer will start working. Obvioulsy I have rebooted everything numerous times. My previous Arris never had a problem once
That's a different issue... Xfinity residential service only supports one device (one MAC address) and a single IP at a time. For activation and testing, connect a computer directly to port 1 of the CM1150V. For normal operation, connect your router to port 1 of the modem. The other 3 ports on the CM1150V are not for additional devices, but rather for using its port aggregation (with proper ISP support and a compatible router).
Thank you for the help, makes sense now. i guess that's why there were black tabs in port 2,3,4 :)
