IPv6 unreachable

Hi All,

The last few days IPv6 routing seems spotty (working most of the day but not working for a few minutes every few hours), currently it’s not working and I don’t know why.

Are there known issues? Is there something I can do to debug? Is there something to provide?

A traceroute shows there is no route to the host tested from 2 datacenter networks in 2 different countries. I have no issues reaching other v6 services or accessing v6 test sites (which all indicate my v6 connection is good) so the probleem seems to be isolated to my Fly v6 address.

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Hi, could you post a traceroute to your app’s IPv6? You can email me at [email removed] if you’d rather not post it publicly.

I’ve been seeing exactly the same thing. It seems very sporadic and my appsignal monitoring thing regularly (i.e. ~ 50 times a day) showing uncontactable from various regions - but no clear pattern from what I can tell.
My initial guess was that it something to do with having Cloudflare set up for the domain, but this post is making me think it’s something else.
If it’s ok, can I mail you our IPv6 address too, Lillian? This is starting to cause problems.

@user76 that could be quite a few different issues especially since you have Cloudflare set up.
some questions that might help: what errors are you getting / what exactly does “uncontactable” mean? does your monitoring go through cloudflare? does connecting to your app directly (skipping cloudflare) work? have you taken a look at your app’s logs?
I’m happy to help but I need a lot more information to be able to figure out what’s going on.

I have shared my traces via e-mail, thanks for taking a look.

For added reference, I have no Cloudflare or other proxies in between, direct connections only.

Let me know if and what we could best share (apart from traceroutes) to help figure this out!

I got both of your emails. You’re in the same public IPv6 subnet. I shared @stayallive’s traceroutes with our hosting provider, I’ll post here when I hear back from them.

Sent mine as well.

Note that querying fly.io directly also doesn’t work on my end:

> curl -I -6 https://fly.io
curl: (7) Failed to connect to fly.io port 443 after 4233 ms: Couldnt connect to server

> curl -I -6 https://www.google.com/
HTTP/2 200

I didn’t even think to try that, but yes indeed fly.io is also broken.

Just arrived home and also tried it from my residential internet in NL (previous eyes were from datacenter NL and DE) and also not routing from here, just in case it’s relevant I’ve also shared that traceroute via e-mail.

We tracked this down to a misconfiguration on our edge hosts due to a Linux kernel upgrade. It should be fixed now.


YES. Thank you for the quick action! It al seems to be stable again. Pfew.

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