Need Help Getting IPv6 Internet Working (Network Illiterate)

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Unconnected

Occasional Visitor
For the longest time I thought my ISP (Comcast) was late rolling out IPv6 in my area. It turns out, they’ve had it this whole time and there is something about my setup that I need help diagnosing what’s wrong.

Router: ASUS RT-AC3200
Modem: Arris SB8200
ISP: Comcast

I have to be honest, I used to know a lot more about networking than I do now. I’m a programmer that seems to have lost that part of my brain. I have seen the genius here and am hopeful someone will see something that Comcast, Asus, and Arris haven't (I've spent countless hours on the phone w/ each already and am getting bounced around).

This is my test-ipv6.com result:
test-ipv6.png

Router config:
router-ipv6-settings.png


Router log:
router-system-log.png


Routing table:
router-routing-table.png



Comments:
  • So it seems like it is creating IPv6 addresses locally, which I've confirmed on various devices (Windows 10, OS X, iOS, etc) and I thought I configured it to suggested spec (IPv6 Firewall on). The configuration info appears to be retrieving what it needs from the ISP. The thing that stands out is a missing WAN gateway, which I've tried to set to SSH into the router and set `ip route add default via fe80::1 dev eth0`, which didn't seem to do anything -- unsure if I would need to restart any of the services (I didn't).
    • Arris says the cable modem is PnP and it is IPv6 ready, everything else is reliant on the ISP and Router
    • Comcast says ASUS is the issue
    • ASUS says Comcast is the issue
    • Neither have stated what the issue is and I'm left frustrated and confused
  • I don't have a Comcast business account, but their business page specifies:
    • Default IPv6 Gateway will be dynamically learned by IPv6 compliant and enabled hosts connected to the LAN of the Business IP Gateway. The default gateway for IPv6 is no longer learned or transmitted using DHCPv6, IPv6 router discovery is how hosts or nodes learn their IPv6 default gateway. The IPv6 default gateway will be the IPv6 link local address of the LAN interface of the Business IP Gateway.
  • I have an unboxed ASUS RT-AX82U I purchased for WiFi6 I can use, but I was thinking if I can’t get IPv6 working on this AC3200, then I might return it for a different brand
  • The router driver had been updated to most recent and now I've installed ASUSWRT-Merlin firmware; neither seemed to fix this issue
  • I've enabled/disabled firewall and have yet to have a successful IPv6 test
I'm at a loss and at the mercy of SNB.
 

L&LD

Part of the Furniture
You seem to have jumped around with the version and fork of which firmware you're using/testing. After flashing the version, you wanted to test, did you do a full reset to factory defaults? Followed immediately with a minimal and manual configuration of the router to suggested defaults to secure the router and connect to your ISP? Without using a saved config backup file, either?

What specific firmware are you running? 'Latest', is not specific enough. :)

Is your modem in Bridge mode? Is your router getting a Private IP on the WAN? Are the settings you're using for IPv6 the ones recommended by your ISP?

Can you put your modem in Bridge mode?

What client device(s) are you using to verify IPv6 connectivity?

Did you reboot the entire network (including the modem) after enabling IPv6?

The M&M Config guide may offer some suggestions to put your router in a good/known state so that you can begin troubleshooting better. Please see the link in my signature below for that and other guides too.
 

Unconnected

Occasional Visitor
You seem to have jumped around with the version and fork of which firmware you're using/testing. After flashing the version, you wanted to test, did you do a full reset to factory defaults? Followed immediately with a minimal and manual configuration of the router to suggested defaults to secure the router and connect to your ISP? Without using a saved config backup file, either?

What specific firmware are you running? 'Latest', is not specific enough. :)

Is your modem in Bridge mode? Is your router getting a Private IP on the WAN? Are the settings you're using for IPv6 the ones recommended by your ISP?

Can you put your modem in Bridge mode?

What client device(s) are you using to verify IPv6 connectivity?

Did you reboot the entire network (including the modem) after enabling IPv6?

The M&M Config guide may offer some suggestions to put your router in a good/known state so that you can begin troubleshooting better. Please see the link in my signature below for that and other guides too.
Thank you for your consideration here.

I had factory reset it in the past, but haven't done it lately. I'm hoping to first diagnose that I am receiving the information I should see and have set things up properly before moving on to a complete restore. This router has 3 bands, used for different SSIDs and I am trying not to re-configure if I can avoid it. Not to mention, others are dependent on it during this COVID crisis and I no longer have a laptop with a ethernet port in case I can't connect via wifi to configure it.

The fact that I'm seeing WAN IPv6 Address (and DNS settings), both of which are authoconfigured (router reaching out to ISP) makes me think I'm so close. I just don't know how to read that Routing table or if that WAN Gateway is necessary.

QuestionAnswer
After flashing the version, you wanted to test, did you do a full reset to factory defaults? Followed immediately with a minimal and manual configuration of the router to suggested defaults to secure the router and connect to your ISP? Without using a saved config backup file, either?As a short answer, No. The router has not been recently reset to factory settings. I should point out, I had reset it in the past (a year or so ago) when first looking into this issue, to no avail. I do have IPv4 connection and am getting that IPv6 DHCP autoconfig information for IPv6, which I was hoping to look over first before moving on to more drastic measures (losing my configuration).
What specific firmware are you running?
Previous: 3.0.0.4_382_52288 (ASUS)
Now: 384.13_10 (ASUSWRT-Merlin)
Is your modem in Bridge mode?It is in "Wireless Router" mode and not "Access Point" or "Media Bridge" mode
Can you put your modem in Bridge mode?The setting is available, but why would I? the router is connected to a cable modem via ethernet and devices connect through the router. They don't use other
What client device(s) are you using to verify IPv6 connectivity?Various browsers on Windows10, OS X, and iOS devices. Also ping6 in terminal. Do you have a suggested alternative?
Is your router getting a Private IP on the WAN? It's not a business IP if that's what you're asking. If you're asking for something else, could you describe where I should look? Running `ifconfig` from the router I see Global and Link IPv6 addresses for `eth0` and `br0` -- I'm not sure what that is.
Are the settings you're using for IPv6 the ones recommended by your ISP?As much as I'm aware. It's Comcast. They aren't being helpful in debugging it, since it's not their rented-out hardware.
Did you reboot the entire network (including the modem) after enabling IPv6?Yes, many times. Powered down router and disconnected modem from wall. Tried variations of powering up modem, then connecting router and powering it up after modem connection; as well as powering them both up at the same time.
 

L&LD

Part of the Furniture
Even if you had performed an M&M Config immediately prior to flashing the RMerlin 384.13_10 firmware, I would suggest you do so again. No telling what issues jumping from 382.xx to 384.xx nodes is causing you. Even above the obvious ones you're seeing now. with IPv6 connectivity.

If you want your router to provide full security for your network (recommended), then you want to kick your ISP off your network and use Bridge mode.

With Bridge mode, your ISP will issue your router a public IP and not a private one. This may be all that is needed to get IPv6 working on your ISP, network, firmware, and equipment. But this is only after you perform a full M&M Config (sorry, you won't be able to get around that).

The link below will explain public and private IP addresses better. A public IP doesn't need to be a 'business IP'. All that means is that it will be a static IP and not subject to randomly changing.

.
 

Unconnected

Occasional Visitor
Even if you had performed an M&M Config immediately prior to flashing the RMerlin 384.13_10 firmware, I would suggest you do so again. No telling what issues jumping from 382.xx to 384.xx nodes is causing you. Even above the obvious ones you're seeing now. with IPv6 connectivity.

If you want your router to provide full security for your network (recommended), then you want to kick your ISP off your network and use Bridge mode.

With Bridge mode, your ISP will issue your router a public IP and not a private one. This may be all that is needed to get IPv6 working on your ISP, network, firmware, and equipment. But this is only after you perform a full M&M Config (sorry, you won't be able to get around that).

The link below will explain public and private IP addresses better. A public IP doesn't need to be a 'business IP'. All that means is that it will be a static IP and not subject to randomly changing.

.
I'll take the plunge this evening for a factory reset, but I suppose I can test the bridge mode right now.
Update: I cannot put the router in bridge mode even if I tried, it's to create a wireless bridge and this is the only wireless access point. To describe the network topology again;
  1. there is a Arris modem connecting to the ISP (via coax);
  2. connected to the modem is an ASUS router (via ethernet);
  3. connected to the router are 20+ devices (all wireless, except one 1 ethernet)

Regarding the public/private IP address. From the sound of it, it's less about static IP and just whether it's an internal LAN (192.XXX..) vs WAN address. I'm not up-to-speed on IPv6, but my assumption is if it begins "fe80::" that's a private (internal) address.

Looking at an iPhone, I've got the following network settings for the connected WiFi:
  • Router: shows an fe80:: address.
  • The iOS device seems to have been issued two IPv6 addresses both beginning with "2601::".
    • Both of these addresses have the same LAN IPv6 prefix in the images on my initial post. Is that normal?
    • Note: they don't have "2001::" prefix, which would have been more like the WAN IPv6 Address (in the image on my initial post). This doesn't look out of the ordinary, but I also am not an expert here.
I will also add that it is not the iPhone hardware/browser and must be an issue somewhere between my router/modem/ISP. If I switch to LTE on the phone (cellular carrier), I pass the test-ipv6.



Also: to anyone that can help me get this working, I'll be asking for your Venmo / Cash App. I know it can be frustrating to troubleshoot these problems online, especially with lots of back-and-forth.
 
Last edited:

Unconnected

Occasional Visitor
@L&LD I have followed all your instructions per your other post. Factory restore, set all those settings (even turning DOS attack off and short preamble for 2.4GHz band). I have new SSIDs (old PWs) and rebooted twice (5 mins apart), saved config.

Then I enabled IPv6 to 'native' and no dice. I'm in the same position I was at before this, now with SSH off. Any suggestions?

Also, as mentioned, I'm not sure what you mean by Bridge-mode as I simply can't set it to Media Bridge because it's not a router connected to another wireless router, but I don't think I need to either.
 

L&LD

Part of the Furniture
The Asus router is not meant to be in Bridge mode. The ISP's modem is. Can you enter the Arris' modem/router web GUI and see if you can enable Bridge mode there? If you can't find such a setting, your ISP may need to do that from their end.
 

Unconnected

Occasional Visitor
The Asus router is not meant to be in Bridge mode. The ISP's modem is. Can you enter the Arris' modem/router web GUI and see if you can enable Bridge mode there? If you can't find such a setting, your ISP may need to do that from their end.
I have an Arris SB8200. There is no such configuration for Bridge mode (accessed via 192.168.0.1). Likewise, I called Comcast and they said they couldn't configure my modem. The person on the phone mentioned that setting a 'bridge' mode on the modem didn't make sense and that's only for wireless.

If you know a little about this particular modem, I should add that I may have discovered the issue. There is only one setting I seem to be able to control through modem's interface, Link Aggregation Configuration (previously enabled):
1603165050686.png

When I disabled it, it required a modem reboot. I then also rebooted the router. Upon restart, it now has a WAN IPv6 Gateway (!) and guess what else... can now pass IPv6 sites. I am curious though if I am giving up something by disabling the aggregation, or if I could configure ASUS to work with this configuration.

The gateway is using a full "fe80::XXX:XXXX:XXXX:XXXX" address with UGDAE flags. I thought fe80 was an internal mask, does anyone know where this is coming from? Or is this supposed to be internal to ISP's servers?
 

L&LD

Part of the Furniture
If you're getting your fully paid for ISP speeds, you are not missing anything.

Consider the issue solved. :)

Even if your ISP is ignorant of what bridging the modem is/does.
 

Unconnected

Occasional Visitor
If you're getting your fully paid for ISP speeds, you are not missing anything.

Consider the issue solved. :)

Even if your ISP is ignorant of what bridging the modem is/does.
More than ignorant. They say they can't access my modem, but I seem to recall whenever there's a firmware update, I think they need push it out to the modem. It's so silly. Regarding that fe80 gateway. I'm curious what device it points to because should anything happen I want to know what I should look up to hardcode it.

The ISP agent that answered the call did remind me of Google DNS servers, which I had previously forgot. I'm curious if they would be any faster for browsing the internet. It's something to test. Also, your other minimal configuration reminded me to test the various channels/frequencies. This will be important for a wireless FPS gaming rig, which would really need as good as it can get for click-registry. That's another reason for wanting to get IPv6 working ... to see if any of the game servers are able to give a preferred route for the that data-traffic.

Either way, thanks for you help. Feel free to post your cash app / Venmo.
 

L&LD

Part of the Furniture
No need for compensation, glad to help and you're welcome.
 

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