Hi all,

I have an issue in some strange geographic situations.
My mobile operator (in France) use ipv6 only tunnels/NAT64/DNS64 to ipv4 services.

My mobile (iPhone) have only an ipv6 public address and in some locations I am unable to contact my ipv4 only services which are hosted behind a CCR2116 with port-forward to a Linux server.

I have this issue with UDP and TCP services.

When I use ipv6 address of my services I have to issue. Of course other ipv4 only services (majority of websites) do not have any issue from the phone. Also, my VPN tunnel endpoints on the CCR do not have the issue. Only ipv4 services forwarded to another server behind the CCR.


I suspect something about MTU or MSS, Is there something special to do on the CCR2116 to workaround this issue ? On ipv4 firewall ?

Thanks

i suggest you to make a capture of traffic on ccr side of that specific connections/traffic to see if you notice something strange

Hello,

I made 2 tcpdump traces on the server itself, not the CCR.
Here are the files :
- lte.txt : 2 failed requests from phone when connected on LTE network (ipv6 only with NAT64/DNS64)
- wifi.txt : 1 success request from phone when connected on a Wifi network (ipv4)

Except differents MSS first requests, i didn't see anything strange, but i am not sure...

The problem is that i am unable to reproduce the issue, because it is very related to the mobile operator physical location configuration... In some places it works, on other places, it does not work (ipv6 to ipv4). Note that ipv6 to ipv6 always works.

What is your opinion about these ?

thanks