Deco M9 plus prevents access to local network when internet is down

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Deco M9 plus prevents access to local network when internet is down
Deco M9 plus prevents access to local network when internet is down
2020-10-10 12:43:15
Model: Deco M9 Plus  
Hardware Version: V2
Firmware Version: 1.2.12 Build 20191014 Rel. 42025

I'm not sure how to find the hardware version on my Deco M9 plus. Near the serial number on the bottom is says v 2.8....

 

I have been troubleshooting a bad cable modem connection recently. My Cable modem serves a web based interface to view logs and change settings. When the internet is connected, and all the lights on my Deco units are green, I can connect to my modem's address at 192.168.100.1. When the internet connection is lost, and the lights turn red, I can't connect to the modem anymore.

 

I would like my local network to still work, even when the external internet connection is down. How can I do this?

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#1
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9 Reply
Re:Deco M9 plus prevents access to local network when internet is down
2020-10-12 16:24:40

@DanielW 

 

You probably have something wired to the main Deco other than the modem, maybe a switch to the other port?

 

If you do, disconnect that and connect to the main Deco via Wi-FI.

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#2
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Re:Deco M9 plus prevents access to local network when internet is down
2020-10-13 00:56:29

@Tony I have my Motorola modem connected directly to the main deco. I also have a netgear 4-port switch connected to that same main deco. Everything else is wifi or ethernet to one of the other deco units.

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#3
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Re:Deco M9 plus prevents access to local network when internet is down
2020-10-13 20:07:24

@DanielW 

 

What happens is when the internet is lost the Deco no longer knows where the internet is coming from so the LAN ports get confused. If possible connect the switch to one of the satellite nodes instead.

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#4
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Re:Deco M9 plus prevents access to local network when internet is down
2020-10-19 12:48:02

@Tony I'm not sure what you mean by "connect the switch to one of the satellite nodes instead". The diagram below shows how I have things setup. I would expect to be able to access the the modem interface from my Desktop regardless of whether the Modem had internet access. Instead what happens is that all local network traffic (e.g. 192.168...) stops routing.

 

  

   +---------+   E   +--------------------+   E   +-------------------+  E  +-------------+
   |  Modem  +------>+ Deco M9 Plus (main)+------>+ Netgear 1G switch +---->+Phone device |
   +---------+       +--------------------+       +-------------------+     +-------------+
                             | W
                             v
  E=Ethernet         +-------------------------+
  W=Wifi             | Deco M9 Plus (secondary)|
                     +-------------------------+
                          | E
                          v
                     +----------+
                     | Desktop  |
                     +----------+
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#5
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Re:Deco M9 plus prevents access to local network when internet is down
2020-10-20 16:37:13

@Tony @DanielW I have a similar setup, so I'd like to request this as a future feature: 

 

The ability to set one of the ports on the "main" Deco as WAN only, so if internet goes down, the LAN stays up (even this switches plugged into the main Deco).

 

It's a "standard" feature of most regular wireless routers because they have a stand-alone WAN port.

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#6
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Re:Deco M9 plus prevents access to local network when internet is down
2020-10-21 15:58:21

@DanielW 

 

If you were to disconnect your switch from the main Deco, then disconnect the internet, does your desktop still have a local IP address? If so, what is it? And are you able to ping other devices?

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#7
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Re:Deco M9 plus prevents access to local network when internet is down
2021-11-30 00:58:59

@DanielW 

 

Sorry for hijcaking old thread.

 

I have the exact same problem. I had internet connection down for few hours and could not connect to my server which is connected by wire to same Deco M9 plus as my modem. It really should have dedicated WAN port if the Deco device gets confused when WAN is down. My other Deco devices are in other locations and can't move the server.

 

Have there been any other solution to the problem? This issue is very important to me.

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#8
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Re:Deco M9 plus prevents access to local network when internet is down
2021-11-30 02:27:49

@DanielW I never found a solution. If I want to check the modem, I am forced to carry a computer to it and connect it by ethernet. This feels like a high priority bug to me, but it may be an edge case for this type of device...

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#9
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Re:Deco M9 plus prevents access to local network when internet is down
2021-11-30 07:43:28

@DanielW @Ripa 

Hi, it is suggested to have a look at this link:

 [Deco] WAN/LAN auto-sensing

And I would like to follow up on your case by email and please check if you have got an email from me.

Thank you very much.

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#10
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