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Community Fibre IPv6 Mysteries

Barnet

ULTIMATE Member
In many ways it doesn't matter to me, but as a "toe in the water" on IPv6 (and because my IPv4 connection is via CGNAT) I set up a Think Broadband monitor on my Community Fibre IPv6 address. The address I'm using is a /64 address and looks "likely".

The monitor is clearly terminating at my router as I needed to set the IPv6 interface to respond to ping before it started working at all.

This works for 8 days then stops working and the address has become an address starting with FE80 (so not as far as I can tell a "correct" address). I can fix this by a router reboot.

It is more or less 8 days to the minute after a router reboot that the monitor stops working.

I guess it is the IPv6 DHCP lease renewal process failing between my Draytek router and Community Fibre. The router says "DHCPv6 Client" and the connection itself (in the IPv4 form) all works fine for more than 8 days.

I have no other IPv6 traffic but I can see the data counters clocking up while it is working. I haven't watched what happens to the counters when it stops working. I'll check that next week.

I've still got the indicated IPv6 packet loss of a few percent as well but that is probably something else.
 
Interesting observations. I've just taken a look at my PfSense box and haven't seen any disruptions during the IPV6 DHCP renew period. I'm maintaining a valid "2a02" starting address and haven't seen any local/loop back addresses issued. I suspect this could be a Draytek quirk.
 
@Matt.Rowley.1990

I was (and am) minded that (unlike the packet loss) the failure to renew the IPv6 address is a Draytek quirk.

When working, the IPv6 /64 starts "2A02".

I did ask Draytek's support if this was a "known issue" but apparently it works OK with their IPv6 connection.

I have known DHCP have what seemed to be a response time problem (I "retired" a Netgear many years ago for what seemed to be that problem).

I can't think of anything else easy to do to investigate this matter further.
 
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Set your Draytek to auto reboot every 7 days.

For a 2925

Dashboard

System maintenance

Reboot system and select your reboot schedule (you have to set that up prior using)

Dashboard

Applications

Schedule

Mine is set weekly in early hours Sun morning.
 
@kommando828

Thanks for the detailed instructions on a scheduled reboot on my Draytek.

It might come to that but I've still not given up hope of doing something on my side that makes the DHCP renewal (assuming that really is the problem) work.

I've found that everything else on my Draytek will be fine for months. It is generally config changes that cause me to reboot it rather than anything else.
 
@Barnet local ipv6 addresses start with FE80: and as you state it's not correct but if Community Fibre ipv6 is setup correctly at their end then it shouldn't be possible to receive a FE80: address as a wan IP address.

I would raise a technical support ticket with Community Fibre the next time it happens advising something on their network is handing out local ipv6 via DHCPv6 and the FE80 gateway address is:

As if it happens again you could potentially access someone else's home or business network.
 
@meritez

Thanks for the suggestion. If I were more confident about my Draytek configuration I would contact Community Fibre.

My current thinking is that something about my Draytek IPv6 config makes the lease renewal fail.

Draytek's support say that IPv6 WAN DHCP works (and I'm highly inclined to believe them).

Unrelated, something changed overnight last night in the Community Fibre IPv6 world (I had been sent a planned engineering works notification a few days before).

A little after 11pm it seems that the IPv6 service dropped. It may have returned with a different address at that point but I can't easily tell.

My Draytek suggests that the current IPv6 address was issued at 2:30am (or at least last renewed then) and it is a very different IPv6 address (no long run of "0000" in it) to the one I had had for about 5 weeks.

The IPv4 service had two short blips, one after 11pm the other at 2:30am. It came back with the same CGNAT IPv4 address and I still have the same (shared) public IP address.

I now need to wait for 8 days and see what happens.

Early indications are that the Think Broadband monitor IPv6 packet loss remains as before.
 
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@meritez

Thanks for the suggestion. If I were more confident about my Draytek configuration I would contact Community Fibre.

My current thinking is that something about my Draytek IPv6 config makes the lease renewal fail.

Draytek's support say that IPv6 WAN DHCP works (and I'm highly inclined to believe them).

Unrelated, something changed overnight last night in the Community Fibre IPv6 world (I had been sent a planned engineering works notification a few days before).

A little after 11pm it seems that the IPv6 service dropped. It may have returned with a different address at that point but I can't easily tell.

My Draytek suggests that the current IPv6 address was issued at 2:30am (or at least last renewed then) and it is a very different IPv6 address (no long run of "0000" in it) to the one I had had for about 5 weeks.

The IPv4 service had two short blips, one after 11pm the other at 2:30am. It came back with the same CGNAT IPv4 address and I still have the same (shared) public IP address.

I now need to wait for 8 days and see what happens.

Early indications are that the Think Broadband monitor IPv6 packet loss remains as before.

Yeah, I had the planned engineering works last night. Interestingly, I had to reset my DHCP6 lease as I noticed the gateway was showing down this morning. Upon resetting, IPV6 came back and as you say, retained the same IP and unfortunately the same packet loss.
 
@Matt.Rowley.1990

On closer inspection, while the "odd" address I had from 2:30 this morning would work for a Think Broadband monitor, I had no DNS servers.

After a reboot of the router I ended up with an IPv6 address that was much more like my original one ( however different in the last 4 digits) but I had the blocks of many zeros back. It is still a /64.
 
Is there still a Community Fibre issue with IPv6 failing to work when one has a static IPv4 assigned on the account - or did I dream that?
 
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Thanks to the OP for this thread, I just had my 3Gbs (resident) installed this Saturday (after 4~5 months of power issues on the pole and main exchange).

They provided me with an Asus router (RT-AX89X), however, upon checking, I found out I have no ipv6, for some reason, I assumed they only have ipv4, but then I remembered they provide both, after reading this thread and others' posts, I have decided to drop them an email inquiring about the ipv6.

Unless I am doing something wrong or my setup was not correct, I don't know... in the router option, it shows ipv6 enabled as a passthrough.
 
Last edited:
Thanks to the OP for this thread, I just had my 3gbts (resident) installed this Saturday (after 4~5 months of power issues on the poll and main exchange).

They provided me with an Asus router (RT-AX89X), however, upon checking, I found out I have no ipv6, for some reason, I assumed they only have ipv4, but then I remembered they provide both, after reading this thread and others' posts, I have decided to drop them an email inquiring about the ipv6.

Unless I am doing something wrong or my setup was not correct, I don't know... in the router option, it shows ipv6 enabled as a passthrough.
Wow, that's a beefy router, considering the standard issue kit from most ISPs. Then again, Community Fibre seem to be the rare breed that aren't like most :).

As far as I'm aware, the 3Gbps plan should also have IPV6 and I would expect the configuration to be the same as others, which is a configuration of DHCP6. I would have expected the Asus kit to be setup correct out of the box but see if that's an option for DHCP on the IPV6 side.

Aside from that, how are you finding the 3Gbps plan? Would love to see a speed test capture.
 
Wow, that's a beefy router, considering the standard issue kit from most ISPs. Then again, Community Fibre seem to be the rare breed that aren't like most :).

As far as I'm aware, the 3Gbps plan should also have IPV6 and I would expect the configuration to be the same as others, which is a configuration of DHCP6. I would have expected the Asus kit to be setup correct out of the box but see if that's an option for DHCP on the IPV6 side.

Aside from that, how are you finding the 3Gbps plan? Would love to see a speed test capture.
Thank you for your reply, I will look into the router setting again and see if I missed something, I have also contacted CF yesterday about the IPv6, waiting to get back to me regardless.

The router is indeed impressive and surprised by it, to be honest, although the techies took 3hrs to get it working, they couldn't figure out how to get the ethernet's in the router to work, it was a simple hidden setting under WAN > Dual WAN and change the Primary WAN to 10G SPF+.

As for the 3Gbs, I haven't yet fully tested its full potential, I am waiting for my 2.5Gbs network card to arrive today or tomorrow and do a fullish test, 10Gbs network cards may be in the future.

But I can show you a few test results I took earlier today.

From my phone:

65746 (1).webp


And from my PC:

13952411727.webp
 
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Be interested to see what it hits later tonight after all the nightclubs and restaurants that are CF customers have shut for the night.
That is a good idea, I'll see if I can run a test very early in the morning, around 5 am or something.

Update, here is one just did for the sake of checking before bed.

13955803343.png
 
That is a good idea, I'll see if I can run a test very early in the morning, around 5 am or something.

Update, here is one just did for the sake of checking before bed.

13955803343.png
You'll probably find there's a few companies that do backups over night so 5am should be good to see.
 
@rain111 - looks like you’ve some way to go before you’re near saturating that 3 Gbps link.

Even with ‘just’ a 2.5 Gbe NIC in the machine it should easily be able to push north of 2300 Mbps on a test run.

I would look at your machine setup, including optimising any AV, spam ware etc on the box.
 
@rain111 - looks like you’ve some way to go before you’re near saturating that 3 Gbps link.

Even with ‘just’ a 2.5 Gbe NIC in the machine it should easily be able to push north of 2300 Mbps on a test run.

I would look at your machine setup, including optimising any AV, spam ware etc on the box.
Spam in the router... there isn't from what I can tell, it's an ASUS setup, and not even a CF skin on it, a factory setup, even came in its original Box, with no branding or anything, if I am missing your point, please elaborate further.

As for my Machine/PC, it's powerful enough to handle it, running it on an SSD and NVMe, just can't seem to reach it, but I'll look into maybe changing the card to another slot in the PCIe and see if that might be the issue.

Optimising AV? I don't follow.
 
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