ipv6 is unreachable

[Anonym96292]

Hi, I can't speak German so I'll write this in English if that's ok.

I need to remotely allow people from work to join an app I'm hosting on my PC but they can't connect. Every test I've done with my ipv6 says that it's unreachable.

I have a 100 MB Unitymedia contract with a DS-Lite router.

I can browse as normal, all my devices at home can access the Internet via Wifi and/or cable.

If I run https://tools.keycdn.com/ipv6-ping, for example, it says that my ip is unreachable.

Things I've tried:
- Disable the router firewall
- Enable a port in Windows in both directions
- Configured the inbound/outbound traffic policy in the router for the same specific port.
- https://ipv6-test.com/ everything seems to be ok.
- the port is opened based on this website: http://www.ipv6scanner.com/cgi-bin/main.py 

Something curious that I realised this morning is that I can only access the app via a kartmobil Nexus 5X mobile I have, but I can't with a Vodafone (Spanish contract) Xiaomi Max 3. Both mobiles had wifi disabled. Tests I've done say that the kartmobil provider supports ipv6, where the Vodafone Spain provider doesn't.

Everyone that has tried to access the app is from abroad Germany. I can't say if this has anything to do with the issue. But because the only device that could join was from Germany maybe it has something to do with the issue.

After a while debugging this issue I can't solve it on my own, so I hope you can help me with this. Thank you.

[Wayne123]

You can't ping internet sites from your internal net? That should work, providing you don't have any ICMP/ICMPv6 filters internaly:

$ ping -6 2a00:1450:4001:824::200e
PING 2a00:1450:4001:824::200e(2a00:1450:4001:824::200e) 56 data bytes
64 bytes from 2a00:1450:4001:824::200e: icmp_seq=1 ttl=55 time=13.3 ms

Or are you talking external->internal? https://ipv6-test.com/pingtest/
IPv4 will fail there but IPv6 should work.

Keep in mind that your IPv6 address may change regularly and you may have multiple addresses on the same interface. If you want a static address you can enable SLAAC/eui64 addressing - you should then have one IP address which is 64 bits your network + 64 bits your MAC. You can use your SLAAC address for incoming (as it doesn't change) and your non SLAAC will be used for outgoing connections (supposed to help hide your identity)

The Cloudflare proxy works great for http/https.

[Anonym96292]

I was talking external -> internal.

That tests fails for both ipv4 and ipv6, 100% loss.

[Wayne123]

Did you add ICMPv6 Any/Any to the Connect Box Port Forwarding? Ping uses ICMP protocol -- so even if ICMP is not working TCP/UDP may be.

[Anonym96292]

Yes, inbound and outbound rules as follows:

All / All / ICMPv6 / All / All / true

[Wayne123]

I would guess then that your server firewall is blocking pings, not the modem. It's not a big deal as long as you can reach the port via TCP/UDP.

[Anonym96292]

Do this proxy services you recommend allow "http://[ipv6]:port" addresses or just "domain.com"?

[Wayne123]

You need to have a domain name registered. Keep in mind Cloudflare will only proxy http/https traffic so it may not work for you.

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