IPv4 not available on router

[reddevil00]

IPv4 DNS is not available on the router and thus I am unable to use a lot of services (including this sky forum). This happens only on laptop devices connected to the main router, all other devices work fine. I have tried using Google DNS but it did not work. If I disable IPv6 on my network adapter or the router itself I lose connection to the internet (because IPv4 doesn't exist I assume). I tried prioritising IPv4 using regisry modifications but it simply switches to IPv6 because it is unable to detect IPv4. On rare occasion it fixes itself, and then goes back to being broken. Please help.

[Phoebe+E]

Hello, 

I've been having this same issue since Wednesday and sky have been zero help.

no advice but hope we get answers. I'm ringing Sky again today.

[Tobz123]

I think I'm potentially having a similiar issue. My phone can connect to the WIFI as well as my PC has connection via ethernet however all laptop devices cannot connect to the network. If you get any update on how to fix please let me know

[Chrisee]

@reddevil00 you will notice that there is a comment "Shared by using MAP-T" against the IP4 address. As you may know the supply of IP4 addresses is exhausted so network operators like Sky have to use techniques where multiple users can co-exist on a shared IP4 address. There are a number of these systems to achieve this the one Sky uses is MAP-T which requires IP6 to work hence the result you observed. Sky's network fully supports IP6 which enables them to use this system as against the better known CGNAT/CGN as it requires far more input at the carrier end. Given it was expected that the switch from IP4 to IP6 would have been completed by now the fact thst it hasn't has to be managed.

My own system has been running MAP-T with a 8:1 share without issue for months with zero impact on apps etc. Sky Italia have been using this method for over 5 years. The forum does see some issues notably with company VPNs where Sky can if it proves necessary disable MAP-T or switch the customer to a 1:1 ratio. However if you have a router like the white Sky Max hub that offers support for MAP-T the Sky servers will use it.

[Tobz123]

Potentially I had a different issue which was solved by rebooting from the router diagnostics:

- Goto "https://192.168.0.1"

- Sign in using username and password (default is username: "admin", passwword on the back of router)

- Click "Maintenence" tab then "Diagnostics" sub-tab

- Scroll down to "Reboot the Sky Hub"

- Click "Reboot" button

- Wait ~5 mins for reboot

[Chrisee]

@Tobz123 sounds like you have a black Sky hub which do not support MAP-T. The method you used, which is not present on the newer white Sky Max hub, forces a reconnection at Sky's end which can clear issues where the server was not rooting  DNS calls correctly. Similar symptoms can have different causes.

[reddevil00]

Hi, did you manage to resolve the issue?

[Chrisee]

@reddevil00 what is the issue you are trying to resolve by the various changes you mentioned in the first post? The introduction of  MAP-T method of sharing public IP4 addreses has gone smoothly for most customers but a few apps mainly company VPNs hit issues which Sky are looking into so are gathering information.

[-rpnz-]

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@reddevil00 wrote:

IPv4 DNS is not available on the router and thus I am unable to use a lot of services (including this sky forum). This happens only on laptop devices connected to the main router, all other devices work fine. I have tried using Google DNS but it did not work. If I disable IPv6 on my network adapter or the router itself I lose connection to the internet (because IPv4 doesn't exist I assume). I tried prioritising IPv4 using regisry modifications but it simply switches to IPv6 because it is unable to detect IPv4. On rare occasion it fixes itself, and then goes back to being broken. Please help.

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The results in this screenshot are perfectly normal and expected on the new Sky Max Hub running MAP-T.   When connected using MAP-T, the Primary DNS Server (IPv4) and Secondary DNS Server (IPv4) fields will not be populated.

The Sky Hub proxies DNS queries to our recursive DNS platform over IPv6 only, this includes both A record queries (for IPv4), and AAAA queries (for IPv6).

Internally on your LAN, the Sky Hub should still be advertising itself to your devices as a DNS server over both IPv4 (via DHCPv4) and IPv6 (via Router Advertisements and Stateless DHCPv6).  

Sorry this isn't much help for your issue, but based on the screenshot alone, it looks OK.   If I had to guess based on the symptoms described, I'd say the client device is missing a DHCPv4 lease entirely?

[reddevil00]

Thank you for your response. When I run ipconfig I don't see any IPv4 addresses at all. I have tried assigning a static DNS(Google DNS).

ipconfig /release gives me "An error occurred while releasing interface WiFi : An address has not yet been associated with the network endpoint."
ipconfig renew gives me "An error occurred while renewing interface WiFi : The DHCP client has obtained an IP address that is already in use on the network. The local interface will be disabled until the DHCP client can obtain a new address." In an attempt to resolve this I reserved an IP for my device from the router admin page, still did not work.

DHCPv4 is enabled on the router:

But still says disabled here:

Hope this helps you pinpoint the issue. Thank you.

[-rpnz-]

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@reddevil00 wrote:

ipconfig renew gives me "An error occurred while renewing interface WiFi : The DHCP client has obtained an IP address that is already in use on the network. The local interface will be disabled until the DHCP client can obtain a new address." In an attempt to resolve this I reserved an IP for my device from the router admin page, still did not work.

So it sounds like another device on your network is squatting on the IP that the Sky Hub is trying to give to this device.  Is it possible that there are any other DHCPv4 servers on your network that are also handing out IPv4 addresses?  No other routers, access points, pihole, etc? or any other devices that have manual IPv4 addresses configured?

If you're confident with Wireshark, the next step I'd do is take a packet capture whilst doing ipconfig /renew  , filter the capture for dhcp and arp, and see if you can see which devices are responding to the ARP who-has messages for the IP it's given.

But still says disabled here:

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That's fine, those are DHCP client daemons and are distinct from the server daemons; they obtain leases from our network.  DHCPv4 client is disabled because it's not needed, as you're getting IPv4 connectivity with MAP-T (over IPv6)

[reddevil00]

We do have a Tplink wifi extender. No issues connecting to the internet via the extender. Would switching it off resolve the issue?

[-rpnz-]

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@reddevil00 wrote:

We do have a Tplink wifi extender. No issues connecting to the internet via the extender. Would switching it off resolve the issue?

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If it's truly a wifi extender it shouldn't be causing issues as it shouldn't be running a DHCPv4 server, but if it's configured as a router, or it's a router and not a wifi extender, then that may explain it.

If it is causing issues, disconnecting it may not immediately resolve the problem, as the clients will retain their rogue DHCPv4 leases until the timers expires.  (which could be any duration depending on the rogue DHCPv4 server's configuration, as there's no industry standard default value).

Does the TPLink have an admin console, can you check to confirm it's not a router/running a DHCPv4 server?

Or power it off, and power off any other devices in the home you're not currently using, and give the problem devices another try.

[reddevil00]

Accessed the Tplink extender admin page and it is in fact in range extender mode. Here is what it says:
"In this mode, the range extender boosts the existing wireless coverage in your home."

[reddevil00]

Here is a screenshot of the settings