Re: Network resets

RonKirkpatrick · ‎2017-09-07

For my own reasons I have my RBR50 configured to run on the network range of 192.168.100.x. Twice now the network range has been reset to 192.168.1.x with a message about the reason being the old range is causing conflict problems with the ISP. Since the entire 192.168.x.x is both RESERVED and PRIVATE and the ORBI is suppose to be handling NAT translation, why would Netgear even think that this is an issue?

TheEther · ‎2017-09-08

Your modem may be using 192.168.100.x.

RonKirkpatrick · ‎2017-09-08

Uh, the modem is on the 71.63.x.x side of the router. I would be very much surprised that a modem on the public side of the router would be using a non-routable ip address.

st_shaw · ‎2017-09-08

@RonKirkpatrick wrote:
Uh, the modem is on the 71.63.x.x side of the router. I would be very much surprised that a modem on the public side of the router would be using a non-routable ip address.

Be surprised then. For example, all the CenturyLink modems have a non-routable IP address assigned to their switched ports (192.168.0.1) which can used to access the modem when the modem is in bridged mode. Any device (such as Orbi) plugged into the modem will get a WAN IP via DHCP.

RonKirkpatrick · ‎2017-09-08

Both devices, Century Link modem and Orbi, should be doing Network Address Translation. Neither device should be putting 192.168.x.x addresses on the public network. The only ports on my Arris TM722 cable modem are 1 Power, 1 Coax, 1 Ethernet (plugged into the Orbi) and 2 Telephone.

TheEther · ‎2017-09-08

Is the Century Link device a pure modem or a modem/router? Because if it's performing NAT, that implies it handles traffic with private IP addresses and must itself have a private IP address.

But that's orthogonal to the point that @st_shaw and I have been trying to make. Even if a device doesn't perform NAT, which would be the case with a pure modem, it can still have a private IP address. The private address is a predictable address that makes it easier to log into the device.

st_shaw · ‎2017-09-08

@RonKirkpatrick wrote:
Both devices, Century Link modem and Orbi, should be doing Network Address Translation. Neither device should be putting 192.168.x.x addresses on the public network. The only ports on my Arris TM722 cable modem are 1 Power, 1 Coax, 1 Ethernet (plugged into the Orbi) and 2 Telephone.

There are several issues here:

1. Orbi is programmed to automatically change its LAN address range if it detects a conflict on the WAN side.

2. You seem to be operating under the assumption that a network device can have only one IP address. That's not true. An Ethernet port or a switch can have multiple addresses, and they can be on different ranges, including routable and private ranges. @TheEther was hypothesizing that your modem was using an address that conflicted with your Orbi LAN. This is a feasible hypothesis.

3. If your network is configured properly you should only have one NAT device. Your comments about both devices doing NAT seem to indicate you might have two NAT devices on your network. That could contribute to your issue.

You should either 1) run Orbi in AP mode, or 2) run Orbi in router mode and run your modem in bridged mode.

If you can describe how things are setup currently, and what your reasons are for using a particular LAN range behind Orbi, that information might help find a solution.

RonKirkpatrick · ‎2017-09-08

I have no knowledge of how my ISP has configured the Cable Modem. I was offered the ISP's WiFi, but I prefer to run my own WiFi Router. I don't like to be limited to what the ISP says I should do. If you think the Cable Modem also has a 192.168.100.x address, I can configure to a different range. I picked this one at random. I don't like "default" network configurations and have a tendency to change things to make it harder to "someone" to break into my network or spoof me into thinking they know about my network. (How many have pressed the "Windows Tech Support" folks for at least the IP address of your computer and been told that it's 192.168.0.1?) For this reason, I change as many things as I can to make my system "non-default".

st_shaw · ‎2017-09-08

Yes, change your address range to something other than 192.168.100.0 and you should be good.

Search the below webpage for "192.168.100" and you will find discussions of Arris modems handing out DHCP addresses in the 192.168.100.X range. What you are seeing may indicate intermittent issues with your cable service. (Or power outages, or you pulled the plug, etc.)

https://news.ycombinator.com/item?id=10596667

From the above link: "When the modem can't access the cable infrastructure, it turns itself into a DHCP server and hands out IP addresses in the range 192.168.100.xx. This is useful for people at home whose configurations are such that their home networks won't work properly without some sort of DHCP server provided by the ISP."

RonKirkpatrick · ‎2017-09-10

well, I've moved to a different range. Time will tell if that fixes the problem.