Discussion Netgear R6800, Access Control and peripheral devices no longer able to connect to the internet - For Info

[PipAlex]

Hi everyone,

I'm posting this just in case someone else has this problem in future. I'm no network geek and still have no idea why/what happened but this is what I know.

I had a Netgear R6800 hooked up to a cable modem and run a smart home, so lots of Azetch/Solwise powerlines, multiple Alexas, tado, nest smoke detectors, a doorbell, hue, quinetic wifi light switches, cameras, along with cat cabling for my pc/network printer etc etc all going into a linksys switch which plugs into the router.

The set up has been running for almost 3 years now without too many hiccups, I added a couple of quinetic switches a few years ago and multiple smartplugs but it's taken it in it's stride and has been rocking along nicely. I've been using Access Control to identify each of the devices and apart from a little contention (these routers aren't supposed to be able to run 40 odd connected devices) it's been pretty smooth going.

A couple (yes, it has taken that long to find the solution) of weeks ago I turned the Access Control to block any new devices connecting (reason is irrelevant but sorted my problem). I only did it for a couple of hours and then flipped it back to the normal setting of allowing devices to connect. Then I discovered that most of my devices reconnected to the network but had no internet connection.

The wired connections still worked but the powerlines stopped working (except to allow my laptop to connect via a cat cable, the others that connected through cat didn't work), the alexas couldn't connect and the tado and hue were out of action too (the hubs for them are well away from the router due to signal problems so I use a powerline).

I did multiple network resets, then far too many factory resets on the modem and the router, got my isp to check the modem and monitor the internet connection for a couple of days and nada - still couldn't get the items to connect and get access to the internet. After the factory reset on the netgear I noticed that the IP addresses weren't being assigned to the ones that could get internet. A fair few factory resets later, I unplugged the netgear and switched my cable modem back to a modem/router.

and discovered that the devices still couldn't connect.

The isp sent out an engineer, he couldn't get them to connect and so swapped the modem/router out. They still didn't connect and the answer turned out to be that each of those devices - the powerlines, alexas, a camera that used a powerline - all needed unplugging and a reset before they could be assigned an ip by the DHCP on the router. Which is what I've just finished doing this evening and everything is back to semi normal. The only thing left to do is plug the R6800 back in but I'm going to leave it a few days to settle down before I even think of putting that piece of kit back onto the network.

So there you have it. I hope the info is useful to anyone who has the same problem and if anyone could tell me how the R6800 did this to some but not all of my peripheral devices I'd appreciate knowing as right now I'm thinking sentient malevolence.

 

[Ralston18]

Interesting.

Being that this is a "Discussion"....

First, as to what happened - my thoughts: When access controls were invoked all worked well until various devices were turned on and off thus receiving new DHCP IP addresses. Then the various resets forced default settings that further caused further conflicts. Especially if someone was trying to do end runs around parental controls. Or outsiders trying to leech in via your wireless network.

Each computer stores network addresses using ARP (address resolution protocol) in a table that shows Internet Address, Physical Address (MAC), and Type (static or dynamic). Who's who information.

[Note: You can see that table by running "arp -a" via the Command Prompt on any given computer.]

All of the network computers and the router had to reestablish their arp tables and the data was likely the proverbial "moving target".

=====

What tools or utilities do you use to monitor your network and devices?

For example: your router may have an admin page that lists all connected devices, their IP addresses (DHCP and Static) and respective MAC's.

FYI - I found the following link:

https://www.downloads.netgear.com/files/GDC/R6800/R6800_UM_EN.pdf

See physically numbered Page 168, bottom section. Print the "Attached Devices" listing for reference purposes. Especially when the network is up and fully running as normal. Knowing/having the MAC addresses can be very helpful for troubleshooting.

[Side bar: Access Controls are discussed beginning on Page 58.]

There are a number of free utilities that will also scan the network to find devices and report similar information and status.
They vary in usefulness, user friendliness, and output data. Be careful about downloading any such utilities - other unwanted apps may come along for the ride.

There are also some DOS and Powershell commands that can be very useful with regards to network control and management. E.g. "netsh wlan ...." can provide a quite a bit of information about the wireless network(s). Note: Must be run on a wireless computer.

The end objective, for you, is to be able to see the big picture and have a sense of what is what.

That, in turn, will help you troubleshoot future problems by comparing past and present. Some things (DHCP IP addresses) are likely to change but if you spot something else that is not as it should be then that would be a troubleshooting lead.

And it always helps to have a simple diagram showing your network: all devices and connections. The diagram does not need to be a work of art per se.

Just enough to, again, see the "big picture". Add labels and notes as relevant and important to you.

Another suggestion: Once you have the router configured and both it and the network working as desired/required then back up the configuration per Page 158.

If you are forced into a router reset (back to default settings) restoring the configuration will be much easier.

 

[PipAlex]

Interesting.

Being that this is a "Discussion"....

First, as to what happened - my thoughts: When access controls were invoked all worked well until various devices were turned on and off thus receiving new DHCP IP addresses. Then the various resets forced default settings that further caused further conflicts. Especially if someone was trying to do end runs around parental controls. Or outsiders trying to leech in via your wireless network.

It's a strange thing alright and unfortunately I didn't screenshot everything as it happened. I actually turned the access control to block new devices as I had something that was flooding my internet connection every minute with something that was making the isp disconnect my link - I only discovered it when I had to log into an email session via a browser and the disconnection kept making me have to log in to get a new session token. Once I'd flipped it over to blocking all new device connections it stopped - so I turned it back to allowing all. During that time all the devices that were connected at the time continued to work but once I turned it back to allowing all new devices to connect that the trouble started.
Before during and after there were no devices connected to the network that weren't mine (well none that displayed as connected anyway).

Each computer stores network addresses using ARP (address resolution protocol) in a table that shows Internet Address, Physical Address (MAC), and Type (static or dynamic). Who's who information.

[Note: You can see that table by running "arp -a" via the Command Prompt on any given computer.]

All of the network computers and the router had to reestablish their arp tables and the data was likely the proverbial "moving target".

I assumed there was nothing I could do from my pc because the pc was working fine during all of it and it wouldn't see what the router was seeing.
My big problem with the devices that were having problems connecting is that with the exception of the alexa echos none of them have an accessible UI unless they're connected to the internet and I can get to them via apps on my phone.
Because initially I still had access control on, devices that were connecting were identified by their assigned IP address, despite not being able to connect. Once I did the first factory reset of the router I saw that the ones that weren't connecting to the internet either had no IP assigned (it was just a dash in the ip address field) or had the default (I can never remember the name, private network ip?) stored in the device - some were 192.168.168.100, others weren't even in the 168 range (ie .10.nnn) I didn't make notes unfortunately.
these odd ip addresses didn't make much sense since none of the devices that were having problems had a static ip coded into the device. So post disaster, the router (s) should've assigned addresses to them either from the list of assigned devices table or dynamically but neither the netgear or the isp's router actually did.
Does that make sense?

What tools or utilities do you use to monitor your network and devices?

For example: your router may have an admin page that lists all connected devices, their IP addresses (DHCP and Static) and respective MAC's.

I use the router's attached devices page. Netgear's is pretty comprehensive. Because it works by mac address to assign the ip addresses I have an excel spreadsheet with the mac addresses and device name of all my devices - including the wifi range extenders and powerlines - thankfully the only things that change their mac addresses appear to be the range extenders but only if they've been unplugged - which is a pita but thankfully they keep within a certain range so I can work out what the device is - the mac address finder helps too. https://macvendors.com/

FYI - I found the following link:

https://www.downloads.netgear.com/files/GDC/R6800/R6800_UM_EN.pdf

See physically numbered Page 168, bottom section. Print the "Attached Devices" listing for reference purposes. Especially when the network is up and fully running as normal. Knowing/having the MAC addresses can be very helpful for troubleshooting.

[Side bar: Access Controls are discussed beginning on Page 58.]

I used that user manual from the get go - what I found is their network reboot suggestion didn't work and I had to reboot the modem again afterwards to restore the internet access. Access control is interesting as it seems there are issues with the access control tables over many brands. It's something to be treated with a bit of caution. When I first started with this isp I used their modem/router and their access control table only held about 5 records (not that they told anyone this) and since I have so many devices I started added them to the AC and discovered that instead of just dropping the earliest in the list (or any variation thereof) it was overwriting some of the old data with the new and promptly confusing itself and me. Thankfully they've expanded the table now. Netgear doesn't seem to have a limit with the table and it's been pretty stable - until it wasn't.

There are a number of free utilities that will also scan the network to find devices and report similar information and status.
They vary in usefulness, user friendliness, and output data. Be careful about downloading any such utilities - other unwanted apps may come along for the ride.

There are also some DOS and Powershell commands that can be very useful with regards to network control and management. E.g. "netsh wlan ...." can provide a quite a bit of information about the wireless network(s). Note: Must be run on a wireless computer.

The end objective, for you, is to be able to see the big picture and have a sense of what is what.

That, in turn, will help you troubleshoot future problems by comparing past and present. Some things (DHCP IP addresses) are likely to change but if you spot something else that is not as it should be then that would be a troubleshooting lead.

And it always helps to have a simple diagram showing your network: all devices and connections. The diagram does not need to be a work of art per se.

Just enough to, again, see the "big picture". Add labels and notes as relevant and important to you.

Another suggestion: Once you have the router configured and both it and the network working as desired/required then back up the configuration per Page 158.

If you are forced into a router reset (back to default settings) restoring the configuration will be much easier.

I will go looking for that netsh and put it on my laptop for the future. I have wireshark on the pc but just assumed it would monitor the pc rather than the network in its entirety. I should go have a decent play with it again to see what it can do.

I still can't work out what netgear did to corrupt the data on the peripherals though - I know that with some devices (alexa again) alexa will store the ip address assigned to it when it's connected but if it doesn't get an assigned ip it uses its default. But what did netgear do to those devices that even when they were connected to another router they couldn't be assigned an ip - despite being set up to expect the router's DCHP to assign the IP?

It's malevolence, I tell you

eta: before I did my first factory reset I backed up the config . when I restored it the access control was a bit of a mess for the items that weren't currently connected - my hunch was that when they were connected they were identified by the AC IP address but the reality was it hadn't actually been assigned by the router ie the router was telling me it was when it wasn't.. but that was last week and I've forgotten the details.

 

[Ralston18]

All in all, a post mortem of any sort is likely to be cumbersome and inconclusive.

For example how did devices end up with 192.168.168.100 - that is indeed quite odd. (Netgear router's default IP is a the commonly used 192.168.1.1, subnet 255.255.255.0)

Not sure about Alexa's and other devices on your network. I would be curious about their default network settings and what happens when they have had a power loss or perhaps were reset.

Establish rules for your application of static IP addresses and reserve via the devices MAC. Ensure that the allowed static IP addresses are outside of the DHCP IP address range allowed to the main router. Reduce the allowed DHCP IP address range to the number of network DHCP IP devices plus a few extra's for guests to use.

Using an Excel spreadsheet is one approach and not at all uncommon. However, that is just one more thing to maintain and will quickly go out of date.

Simpler, I believe, to just print out network information via the router (if possible) or a third party utility.

Advanced IP scanner is one free option and easy to use.

The "arp -a" command can be helpful especially because you are familiar with using MACs to identify devices.

 

[PipAlex]

I have Advanced IP scanner but have ignored it as some of info is at odds with what the router is displaying.

For example one socket has and ip address in the router as 192.168.0.19 but in A-IP that IP address is shown but all other details are blank yet the mac address for the actual device is shown as having a different IP address (192.168.0.9).

So no matter what, at least I know what is what with my excel spreadsheet as apart from some access points everything else keeps it's mac address.

With the devices and power loss, they just relog onto the network and are fine (except for this time with the netgear doing whatever it did). After the reset of the alexas, I logged in again as usual and they were fine. The one thing I didn't do was check the full details under the ip address for the device (alexa shows both an ip address and another 25 char address which looks like a mac address only longer). Once I plug the netgear router back into the network, if it trashes everything again I'll make a note of that number but I'm not going out of my way to trash it just to have a look, I'm afraid.

Technology, eh?

and an edit (why is it I always forget something?) The reason I'm using access control is that it's the only way to assign a consistent ip address to devices (apart from allowing me to ID what they are in the router table so I don't have to keep looking up the mac address). A consistent IP address is necessary for a number of my items as they have a web interface that needs the specific IP address to be able to display the details.