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Modem update kills connection when in bridge mode

Contributor

Modem update kills connection when in bridge mode

I've had a DPC3941T modem/gateway working in bridge mode with my Asus RT-AC68U for many months without issue.  Last week after Comcast pushed an update to the modem I lost all connectivity.  

 

Troubleshooting I found that:

I was able to connect directly (without the router) and have internet.

I was able to introduce the router and get internet if I did not have it in bridge mode.

Once bridge mode was turned on, I lost all connectivity again.

 

I was pretty sure it was the firmware update from Comcast causing the problem so I swapped out the modem with one that didn't have the update.  Everything was working great again (router in bridge mode).  Last night Comcast pushed out a firmware update again (DPC3941_2.3p18s1_PROD_sey) and now I have no connectivity once again.  

 

Anyone know what the firmware is doing to kill my connectivity?  Any way to roll back to the previous version?  

 

Thanks for any tips. 

New Poster

Re: Modem update kills connection when in bridge mode

Hi, I've been having issues with the router since the last update and once again, this update. I don't use the Wifi on the router, it is set to Bridge mode and I've also disabled their public wifi, however the wifi light (5 GHz) is now flashing. Last week when the first update happened and I was having connectivity issues to the modem's admin, I called and the second-tier tech was able to go in there and mentioned that the problem was that the "Comcast Security Feature" which is for security systems, had the Wifi turned on (an area in the modem we cannot access it seems). After this latest update, same problem has come back, so I'm actually chatting with their support now to see if there is a resolution.

 

PS Most people may not even notice new flashing lights and settings changed on their routers which compromise security, so I hope someone has a solution/explaination for us. 

New Poster

Re: Modem update kills connection when in bridge mode

Forgot to mention, I'm in bridge mode too, with a wifi router connected. That seems to be working fine even with the updates, after reboots (both modem and my wifi router). Also to note: I had to move the connection from router to modem from port 1 to port 2 during the first update for it to register the connection. It has been on that port ever since, maybe that's something too?
Silver Problem Solver

Re: Modem update kills connection when in bridge mode

FWIW: We are seeing a few reports of quirky things happening to Comcast gateways, due to firmware updates. There is no way to roll back firmware, they happen automatically. So you just have to wait it out until the next one. Hopefully things will settle down after Comcasts new cloud platform is introduced!

Sometimes simply resetting the gateway, router (if connected in bridge) and restarting a computer can regain a connection if lost.

Yes, when in bridge mode the router would have to be connected to port 1 on the gateway, the other three ports (should) be disabled.

New Poster

Re: Modem update kills connection when in bridge mode

This has happened to me four times this year, after more than 2 years of hassle-free bridged mode operation.  FWIW I've had good luck with doing a factory reset of the gateway and reconfiguring for bridged mode again.  

Frequent Visitor

Re: Modem update kills connection when in bridge mode

I went through this experience this weekend and pulled my hair out.  I finally found this thread and reset the modem to factory defaults.  After enabling bridge mode, everything has been rock solid today.  Knock on wood.

 

The frustrating part for me, is the comcast phone support and technical never suggested a new code version download might be the issue.  I spent an hour Sunday with an on-site technician that failed to provide any value.

 

Is there anyway to review when a firmware upgrade occurs, i.e. the time and date of last upgrade.

New Poster

Re: Modem update kills connection when in bridge mode

Looks like I was hit with the firmware issue this morning as well. Started getting intermittent internet dropping every 20 min or so. Trying the factory reset, reset up bridged mode song and dance and seeing how that goes. If anyone finds a for sure fix, please update.
Contributor

Re: Modem update kills connection when in bridge mode

The only fix I found that worked was signing up for Vonage and getting rid of Comcast's gateway (and voice service).  I now have an ARRIS SB6183 modem and haven't had a single issue.  

 

 

Frequent Visitor

Re: Modem update kills connection when in bridge mode

Grrr...back again.  Reset is holding for now, but what a pain.

Frequent Visitor

Re: Modem update kills connection when in bridge mode

UGH I'm also going through this issue. I thought it was wiring in the home ( 10 year old home with Cat 6 coax) or some other. I have a ASUS AC1900 and the same exact is happening to me. I am able to reproduce it with out fail. Factory reset. Set up wifi,etc. Have connectivity via router. Go via router to place modem into bridge mode and The second I put it in bridge mode it fails and router can't get a IP.

 

What is you procedure when you do a factory reset to the modem and then place it in brigde mode.

Frequent Visitor

Re: Modem update kills connection when in bridge mode


cdroberson wrote:

I went through this experience this weekend and pulled my hair out.  I finally found this thread and reset the modem to factory defaults.  After enabling bridge mode, everything has been rock solid today.  Knock on wood.

 

The frustrating part for me, is the comcast phone support and technical never suggested a new code version download might be the issue.  I spent an hour Sunday with an on-site technician that failed to provide any value.

 

Is there anyway to review when a firmware upgrade occurs, i.e. the time and date of last upgrade.


It's still happening. I was litterally on the phone hours and then I had a tech come out and say all signals look fine. Then he leave I go back to modem and bam. Samething. UGH. It's really making me upset. I am scheduled for another tech tommorow. Now that I found this thread I doubt anything will help short of a new firmware.

Contributor

Re: Modem update kills connection when in bridge mode

I tried a lot of different ways to get it to work.  At one point I could get it to work by first getting the modem working, then putting it in bridge mode and then adding in the router.  Then other times it didn't work......I'm so happy now that I got rid of that Comcast modem.  Haven't had any problems since. 

Frequent Visitor

Re: Modem update kills connection when in bridge mode

Strangely I found a workaround. I set it up from factory default then. With wifi setup etc. then I turn it all off. Wifi,moca etc. but I don't set it to bridge mode. I add in my asus and I have connectivity. The asus pulls a ip of 10.0.0.199 but it get connectivity. I check what is my ip and I get a new one not seen before. But i have connectivity and the family is glad for the time being.
Expert

Re: Modem update kills connection when in bridge mode

FWIW, if you are hanging a stand-alone / separate router off of the gateway device, and the gateway is not in *bridge mode*, you are cascading 2 routing devices which results in an undesirable "double NAT" condition on your home network.

Google "double NAT" for info about it's potential pitfalls.

Frequent Visitor

Re: Modem update kills connection when in bridge mode

While I understand dbl NAT I can't deal with the lack of connectivity. I have repeated the scenario 4 times of once in bridge mode my router can't get a IP address. I went as far as getting a new router fearing that was the issue. Turns out that it happened again on the new router fresh out of the box. Bridge mode>no connectivity(no ip). I have read of the latest firmware bug when this similar thing occurs. So I'm stuck at this point.
Expert

Re: Modem update kills connection when in bridge mode

Completely understood. Just sayin'. Smiley Happy

Frequent Visitor

Re: Modem update kills connection when in bridge mode

FWIW - suggest those with bridge issues and possible NAT issues check the default ip number for router vs modem.  Some modems use 10.0.0.1 - and some use 192.168.0.1-  To avoid problems suggest one simply check modem ip   and then separately change(offline) the router to a different ip sequence       BEFORE going to bridge mode connection.  For example  modem is 10.0.0.1,  router sets to 192.168.0.1 with DHCP enabled- and away you go . or even 172.16.0.1   ( allowable personal ip address also )

 

  

Frequent Visitor

Re: Modem update kills connection when in bridge mode

Thanks for the suggestion. Fo me Modem is 10.0.0.1 and router was already at 192.168.0.10 so it's possible something else causing the issue.
Frequent Visitor

Re: Modem update kills connection when in bridge mode

Try looking up and downloading  NETGEARGENIE   software- which has a lot of capability abd logs and suggestions- AFIK it willo work with some other brand routers- modems

Frequent Visitor

Re: Modem update kills connection when in bridge mode

Thanks will look that up. I did have someone from corporate contact me. They suggested changing a setting in the modem, turning off the MOCA. Also they will investigate this with their hardware people.

 

Authorized Vendor

Re: Modem update kills connection when in bridge mode


Warzau wrote:
 I went as far as getting a new router fearing that was the issue. Turns out that it happened again on the new router fresh out of the box. Bridge mode>no connectivity(no ip). I have read of the latest firmware bug when this similar thing occurs. So I'm stuck at this point.

I didnt read everything, but got a quick question did you reboot the modem when you put it into bridge mode?  Mostlikely your account only allows 1 IP and the modem had that one IP before if you dont reboot the modem it doesnt clear the modem from the CMTS and it sees that you already have an IP..  Every time you change the public side IP you need to reboot the modem..

 

I normally tell please this:

 

  • Upgrade the router to the latest build
  • factory reset the router (clear any settings)
  • reboot the gateway (when in bridge mode)
  • reboot the Netgear once again or have it do a dhcp renew once the modem is online..
-------------------------------------
Network Engineer, IP Engineer, Docsis..; the views expressed on this post are mine and do not necessarily reflect the views of my employer..

Gamer.. Living the dream one catastrophe at a time Smiley Happy ..
New Poster

Re: Modem update kills connection when in bridge mode

Had the same issue (my router is Asus RT-N66U), called support, was transferred to level 2. Even though I switched the modem to bridge mode, the support tech told me that it was not in bridge mode. She tried to switch it to bridge mode several times but no luck; the wifi lights kept on flashing and I had no connectivity. So she said let me try something else, all of a sudden the Wifi lights went out and everything started working. She said: "you are all set" I didn’t even check the settings until the next day when I found out that I couldn’t access my security cameras (the port was blocked). I logged back in and found out that she just disabled the wifi but left the modem in normal mode (not bridge). So now I’m stuck. I set up the port forwarding on the modem for now to get my stuff to work but don’t know what else I can do. At this point I don’t even know if calling support is even worth it…

New Poster

Re: Modem update kills connection when in bridge mode

I have had this issue with an ARRIS TG862 in bridge mode since March. The modem will disconnect the router erratically, even between DHCP leases. It started suddenly, I guess after a firmware update. To discard a HW problem I switched to bridge mode and had been working for months, except that I had lost significant functionality from my router, of course. I tried yesterday to go back to bridge mode and I have had constant disconnects since.

In the midlle I called Comcast Support, but they did not even have a record of lost connection with the modem or connection between modem and router.

Frequent Visitor

Re: Modem update kills connection when in bridge mode

Re the no record of disconnect. It seem on par with my issue. I would get provisioned,etc and CSR would say. Its connected you should be online. While I was here saying "cant' connect" Even when at tech here we reproduced the issue. His diagnostic tools would say the modem was connected but we couldn't connect.

New Poster

Re: Modem update kills connection when in bridge mode

I mean "to discard a HW problem I switched to Gateway mode" - the default configuration. That solved the issue completely. In bridge mode, I still have constant disconnects. I have changed the Asus router firmware from Merlin to Asus, changed the router (to another Asus though), to no avail. Was wondering if it was an issue with the router, but see that others have had the same problem with different routers...

Frequent Visitor

Re: Modem update kills connection when in bridge mode

Yes, I had that for a day or so. That was the only way to stay online. With bridge mode off, orginal configuration. When the tech came and we did put into bridge mode we got knocked off. But after several reboots. When we threw our hands up and just wanted to do a factory reset. Modem reset still in brigde mode and my Asus got a IP address. Like you I though it was the router. I tried 3 different ones. One brand new Asus out of the box and a eero. As of now it's working in bridge mode. I've left it alone and it seems to be stable at the moment. 

New Poster

Re: Modem update kills connection when in bridge mode

For how long have you gone w/o disconnects? My problem is that when I switch to bridge mode and reboot modem and router, I typically get an IP. Then, after a while, I lose it and it takes for me to disconnect the network cable between modem and router to get it back. A modem/router restart does not even work. I wonder if I have to keep restarting it? If after all those restarts you got it to work in bridge mode and it is stable, I will need to try it myself.

Frequent Visitor

Re: Modem update kills connection when in bridge mode

I wrote this really long reply and then the forum burped and lost it. Anyway to make it short I've had it up for two weeks after the tech left. Haven't had a issue yet. I did get a reply from a comcast tech saying that turning off MOCA would help with issues like this. 

Frequent Visitor

Re: Modem update kills connection when in bridge mode

Edit I thought I lost connectivity was the modem turns out there was a outage in my area.
New Poster

Re: Modem update kills connection when in bridge mode

2 weeks is excellent. I had to search to figure out what MOCA was. I cannot find it in the modem UI, so I do not think that I can disable it. But I will try the multiple resets on bridge mode and see if I can get it to work properly. Thanks!

Regular Visitor

Re: Modem update kills connection when in bridge mode

you need to disable bridge mode on your gateway modem/router.

 from google in the very top search bar at the top of the page, type in 10.0.0.1

and hit enter. the page will come up and you need to enter the username : admin

and the password which is password. then on the next page click on gateway, that 

will bring up another page, scroll down to the middle of the page and you will

see a enable and disable bridge mode button, click on disable and you should

have your gateway modem/router working again........your welcome!!!!😀😀😀

Expert

Re: Modem update kills connection when in bridge mode


GADGETHATCH wrote:

you need to disable bridge mode on your gateway modem/router.

 from google in the very top search bar at the top of the page, type in 10.0.0.1

and hit enter. the page will come up and you need to enter the username : admin

and the password which is password. then on the next page click on gateway, that 

will bring up another page, scroll down to the middle of the page and you will

see a enable and disable bridge mode button, click on disable and you should

have your gateway modem/router working again........your welcome!!!!😀😀😀


From my earlier post in this thread;

 

"FWIW, if you are hanging a stand-alone / separate router off of the gateway device, and the gateway is not in *bridge mode*, you are cascading 2 routing devices which results in an undesirable "double NAT" condition on your home network. 

Google "double NAT" for info about its potential pitfalls.

 

Seven month old dead thread now being closed.