Community Fibre - IPv4 port forwarding and IPv6

I joined CF a few weeks ago, realised that there was no IPv4 port forwarding so after a few back fourths they eventually enabled it for my account but doing this has stopped the router getting an IPv6 address and in turn stopped my devices also being allocated a public IPv6.

Queried this with CF and I’m told by their Tech Support that it’s either one of the other and that from a WAN point of view I can’t have 1, so it’s 1 or the other.

Now this isn’t that big an issue but while I didn’t have IPv4 port forwarding I configured a few of my device for IPv6 so that I could access them remotely but this now no longer works.

So is what I’m being told correct that from a router point of view it’s one of the other?

If you are unable to get port forwarding on IPv4 working then its due to you are on CGNAT and you wont be able to have Port Forwarding due to how CGNAT works.

The only way to get Port Forwarding is if they move you off CGNAT (which they probably won't if you are not on their 3Gbit package and if it's a new connection which yours is) so unless they are using some voodoo IPv6 stuff to port forward IPv4 (not really an IPv6 expert) but they might be telling you porkies there.

Unless I am wrong which somebody will correct me.

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Paul

I agree with Paul. V likely that you not being able to port forward to using IPv4 is due to CGNAT. You can confirm this by checking whether your WAN IP in your router is the same as that reported by "what is my IP address" type sites on the web. If you're on CGNAT, they will differ.
To be able to port forward here, you need to be taken off CGNAT and given a publicly routable IPv4 address.

This should be completely unrelated to whether they allocate you IPv6 addresses - unless that have done something very odd indeed that I cannot conceive of.

Or unless they have made a policy decision that they will either provide a public IPv4 address or will provide IPv6 but would not provide both. It is unlikely to be a tech limitation but could be a policy of the company.

I have confirmed that IPv4 port forwarding now works, albeit rather clunkily at the moment as my public facing IPv4 address appears to be changing 2-3 times a day, no idea why unless it's settling in.

After they have made this change my router no longer has an IPv6 public address, when I check in the Linksys router the IPv4 is shown but the IPv6 address is just blank and all the devices within my home now only have a link local IPv6 address whereas previously they were being allocated a public facing IPv6 address.

Their support guy said it's one of the other so if I want IPv6 then I'd have CGNAT for IPv4 and if I want port forwarding then IPv6 would be disabled as a WAN device can't have 2 public facing addresses. This is rather strange as he's saying that the 2 from a WAN point of view can't co-exist which isn't correct unless this is a quirk or limitation of their setup?

Anybody with CF who had port forwarding enabled could they check their Linksys router on the Troubleshooting page Diagnostics tab to see if they have both an IPv4 and an IPV6 address?

In reply to a post by iluvnips:

Their support guy said it's one of the other so if I want IPv6 then I'd have CGNAT for IPv4 and if I want port forwarding then IPv6 would be disabled as a WAN device can't have 2 public facing addresses.

That is Ballcocks™. The whole point of dual stack is that you have two addresses. I'm on Aquiss, and my Mikrotik router has both an IPv4 and an IPv6 public IP address.

But it could be to do with how their network is (badly) designed. Maybe they have one part of the network which has a pool of IPv4 addresses but no IPv6; and they have another part of the network with CGNAT and IPv6. Then they tunnel your session to one or the other.

Adding IPv6 to the part of the network with IPv4 addresses should be relatively straightforward, but if they've chosen not to do this, then you're stuck.

In reply to a post by candlerb:

That is Ballcocks™. The whole point of dual stack is that you have two addresses. I'm on Aquiss, and my Mikrotik router has both an IPv4 and an IPv6 public IP address.

I am with CF and also using a MikroTik (Model number in my sig) and I can confirm that I have both a Public IPv4 and IPv6 and they both work great with Port Forwarding.

In reply to a post by candlerb:

But it could be to do with how their network is (badly) designed. Maybe they have one part of the network which has a pool of IPv4 addresses but no IPv6; and they have another part of the network with CGNAT and IPv6. Then they tunnel your session to one or the other.

The OP is on CGNAT due to new customers not on their 3Gbits Package will be put on CGNAT, CF might be doing some Voodoo stuff on IPv6 to get IPv4 Portforwarding to work, but I am just guessing that the OP just got some BS from support that has no clue.

In reply to a post by candlerb:

Adding IPv6 to the part of the network with IPv4 addresses should be relatively straightforward, but if they've chosen not to do this, then you're stuck.

I think its just down to them being of CGNAT and them getting bad support that has no clue.

It is and they do have it proof shown in the screenshot images here: Whats My IP Address - IPv6 Test

As you can see CF can and do provide both IPv4 and IPv6 Addresses fine, just new customers not on their 3Gbit Package will get put on CGNAT.

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Paul

Can you go to WhatsMyIPAddress and once all loaded and detected your IP Addresses, take a screenshot of that page and then send it to me via Private Message and I will see what you have and don't have.

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Paul

In reply to a post by ian72:

Or unless they have made a policy decision that they will either provide a public IPv4 address or will provide IPv6 but would not provide both. It is unlikely to be a tech limitation but could be a policy of the company.

I know new customers not on their 3Gbit Package WILL be put on CGNAT its states this on their site if you go looking.

If Community Fibre hasn't already, but they should state this on their product page so that the possibly new customer will know this before ordering.

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Paul

@PaulKirby, I've sent you a PM as requested.

CF don't advertise the lack of port forwarding on their man website, which is what caught me out when I subscribed.

I had also spoke to their sale team a number of times and told them how I used the internet with my previous supplier. I ended up lodging a complaint and told them that their main website does not make this clear or even highlight that this feature isn't available and as a result they agreed to enable port forwarding on my account but then the ipv6 side looks now to be disabled?

Edited by iluvnips (Mon 11-Dec-23 11:01:10)