Could you let me know whether you are preferring to swap the SB6141 with S34?

Since the online light was flashing, it was kind of an intermittent issue. Due to a lack of signals, you might be experiencing this issue. I would suggest checking the cable signals to make sure they are in range to avoid this issue in the future.

http://arris.force.com/consumers/articles/General_FAQs/SB6141-Cable-Signal-Level

Hi…. Yes, I’ve had the SB6141 cable modem on my Xfinity network for 10 years…. But it’s only a DOCSIS 3.0 modem and Xfinity has told me for some time now that I’m not running at the full bandwidth of speed available to me…. I get about 260 Mbits/sec download and that is plenty but supposedly I would get quite a bit more if I switch to a DOCSIS 3.1 modem such as the Arris S34… I also bought and installed a new RT-BE88U ASUS router last November…. I’m a retired EE but NOT all that skilled in understanding router or cable modem terminology….  But to answer your question, yes, I have a new, in the box Arris S34 waiting to replace the SB6141 but I fear doing so until I understand better what’s going on with my existing system…

My old router was an Apple AirPort Extreme and for years, any time the power would go down and come back up, the SB6141 and the Apple router would connect without me intervening…. But now I have the ASUS router with the no longer supported Apple router gone…. Based on what I wrote in my post above, if I was to disconnect power to both and reconnect immediately thereafter, I believe the cable modem would get to that 4th step I mentioned above and restart again and again…. Something about how that modem is talking to the new ASUS router is not handshaking well or something???  That’s what I’m trying to understand…. !!!  

I did learn something new last night…. If I REBOOT the ASUS router from its web interface and just watch the lights, it goes through a recognized sequence and just after that completes, the white “connected” light lights and sure enough, I’m connected….  Thoughts???  thanks...

Might check with the ISP. Xfinity is doing a lot of midsplit upgrades. maybe they’re in your area. 

A summary of my issue…. So it’s so long for a “summary”…. 

— Previously had the SB6141 cable modem connected to an Apple Airport Extreme router…. Through many power outages over many years, when power was restored those two would automatically sync up and reconnect to the Xfinity network….

— Apple came to no longer build or support routers so I needed to move on to a different router…. Also, the SB6141 cable modem is outdated as DOCSIS 3.0 so I need to upgrade that as well..  I choose to have my own cable modem and router instead of using one of the Xfinity Gateways…. That might need to change if I can’t figure out my current issues…

— Last November I purchased and installed an ASUS RT-BE88U router to replace the Apple router…. Not top of the line but up there…. I got it configured and working although I’m not confident it’s all set up correctly…. Tons of settings…

— I have the cable modem and router on a UPS power backup and I can’t say that we’ve had a long enough power outage to test how or if the SB6141 and the ASUS router can self connect after a disconnect….

— But I did get up on the morning of March 5th and noted the modem and router were struggling to reconnect so there had been some sort of disconnect, likely not power but perhaps at the Xfinity source… I watched for hours while the modem would come up to the final step (connect to internet) but it would eventually fail and start over….   In the cable modem page I would see this (see picture attached separately, note the last two items)..  Registration complete in RED spoke to something not being right???

—After several hours it DID finally connect and see below that same cable modem status page now showing very different entries for those last two items…. Operational and Done….  See a 2nd picture attached separately…. 

— Later in the day, I had Xfinity at my house to try to help me understand what was going on and in the process of doing what the tech needed to do, we broke the physical connection twice (changing out old cables)…. And by the time the tech left, we were STILL unable to get it to connect again….  The cable modem would try but when it would get to that final “connection” step, it would struggle and eventually auto restart and this one on for hours…. 

— Over the next several hours I tried a lot of things but what finally worked was 1) I disconnected the router’s ethernet cable from the cable modem (should not have to do that)…. 2) powered down and back up the cable modem…. Where it had tried and failed to get to the final steps countless times over hours, it now came right up to full sync in no more than about 1 minute…. And I was able to repeat that again and again….

— So I got the cable modem fully sync’d with the ethernet cable disconnected and then reconnected the cable with the router powered on…. Only to see the “connected” light on the router being RED saying “no connection” and staying that way, RED…. I could open the router page and see that “no connection” as well….

— What finally “appeared” to work (??) was for me to remove the ethernet cable from the router but with the router powered ON, unplug and replug in the cable modem, let it come up to full sync and the moment I saw the lights on the modem show that full sync, I immediately plugged in the ethernet cable and between 10 - 20 seconds later, the router would change and show “connected”…. I thought that crazy so I did it more than once with the quick plug in of the ethernet cable to the router somehow (??) seeming to play a role….

-- At least once when I got it reconnected, I would at first see a 192.168.x.x (with the x’s filled in) for a WAN IP address as if it was just getting that from the cable modem locally…. Then 20 minutes later I took another look and noticed that now the router had a WAN IP address that was a Comcast/Xfinity supplied number beginning with 174.160.x.x…. Hmmm…. Just reporting that but I don’t understand how that IP address assignment works…. 

— I’ve done many experiments since and the only one that seems to work is to do what I said immediately above???  And one other…. I have now been able to go into the router page, request it to reboot, which it does…. I watch all the router lights go down to only the power light and then I watch them all come back in a repeated sequence with the final part of that being the solid ON power light flashes off to on three times and within seconds after that, the system connection light goes to white meaning the system is connected….

Thoughts on any or all of that???  Sorry it’s so long…

See two attached pictures I could not get to attach to the write up above…

First picture

2nd picture