OpenVPN works with Airtel 4G IPv4 and not with IPv6

[cwaluv]

I am using Airtel sim. I am able to use my Home OpenVPN and OpenVPN (via Linode). OpenVPN only works when Airtel 4G has IPv4. Whenever Airtel 4G changes to IPv6, all my OpenVPN's stop working. Later, just to test, I disabled and enabled Airtel sim on my phone and then I got IPv4 and my OpenVPN's started working again. What is happening here? Anybody?

 

[Chip]

All cellular providers..not sure about BSNL/MTNL duo...use a dual stack nowadays..a CGNAT v4 + public IPv6 address. Why are you using it over mobile instead of fibre? With fibre you can get a static v4 public IP.

 

[cwaluv]

I have OpenVPN setup with a Static IP using pfSense firewall in my house. When I travel, I connect to my home network using OpenVPN with Airtel 4G on my phone. Whenever Airtel 4G is using IPv4, I am able to connect to my home network and when Airtel 4G uses IPv6, I am not able to connect to my home network.

Later, just to test, I disabled and enabled Airtel sim on my phone and then I got IPv4 and my home OpenVPN's started working again. What is happening here? Anybody?

 

[Chip]

Your phone will 1st get a v4 and then it'll use the v4 to get a v6 via RA/DHCP6. That's how its done even on fibre connections.

So if you expect only v4 connectivity you're out of luck.

 

[cwaluv]

You mean to say whenever my Airtel 4G uses IPv6, I cannot connect to my house OpenVPN thats configured using Airtel XStream fiber Static IPv4.

 

[Chip]

What I am saying is that this behavior ie dual stack is default behaviour on all carriers. There's no way to get around it.

When a remote server doesnt respond to v6 it should automatically switch to v4 at least in theory. I can ping my mobile phone's IPv6 address but not the mobile's v4 as it is a CGNAT, from my desktop machine. And I am sure it would work the other way around too...if an iPhone allowed me to use ping. Have you set up incoming firewall rules? Also start using a dynDNS or similar service to map your IPs to your domain.

You may also want to see this - How to use OpenVPN to access your home network through the Wi-Fi Routers

 

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[cwaluv]

Sorry, I'm not using TP-Link router. My OpenVPN is setup using pfsense firewall on my custom PC with Intel Quad Port NIC. Everything is setup perfectly. Anyways, I have a question for you. When will IPv6 become standardized in India?

 

[cwaluv]

Sir, you didn't understand my question. I already have a Static IPv4 from Airtel XStream fiber which I have used to configure my OpenVPN in pfsense firewall. Why would I need dyndns when I'm already paying for a static IP address ₹199/month?

Maybe, I didn't phrase my question properly. That's why you couldn't understand.

 

[Chip]

Your phone is trying to find a v4 address using v6 that's why you cannot connect. You don't need a TP-Link router to follow the instructions there just follow the principles outlined. I use pfSense too but without OVPN as a gateway...Check the pfSense support forums at Netgate.com for detailed help. They have a wealth of info there including setting up firewall rules - OpenVPN Remote Access Configuration Example

 

[AAK]

In short - ipv6 can connect to only ipv6 addresses and ipv4 to ipv4 only.
You have static ipv4 on fiber and you have to connect that with ipv4 only.
To connect with ipv6 from mobile , configure ipv6 in your fiber router and openVpn.

 

[Chip]

@cwaluv Just to add to what @AAK said above, in Airtel fibre, if you get a static IP you won't get a dynamic IPv6 at all. So if you need a v6 you have to go via dynamic v4 allocation.

 

[AAK]

@Chip have you tried Warp Zero trust ?

 

[cwaluv]

Thanks for the information. I have more than decent knowledge of networking, subnetting with IPv4 and not with IPv6.

My OpenVPN was working properly with Jio 4G but 2 weeks ago it stopped working. I think that's when Jio stopped IPv4 on mobile. Now, I get only IPv6 on Jio 4G and 5G.

Last week, I purchased a new Airtel SIM to test my OpenVPN. Today, morning I couldn't connect to my OpenVPN, I think because Airtel 4G switched to IPv6. I disabled and enabled the Airtel SIM with that Airtel switched back to IPv4 and my OpenVPN started working.

I'll have to read more about IPv6 now.

My Airtel XStream fiber connection has both IPv4 and IPv6. I'll have cancel my static IP inorder to use IPv6.

Thanks.

 

[cwaluv]

if you get a static IP you won't get a dynamic IPv6 at all. So if you need a v6 you have to go via dynamic v4 allocation.

Yeah. I figured that out. Thanks. With PppoE, I was able to see both IPv4 and IPv6. With IPv6, a lot of things change. Right? I have never configured IPv6 in pfsense.

 

[cwaluv]

have you tried Warp Zero trust ?

No. I haven't tried Warp Zero trust. What do you use?