Issues connecting to IPv6 of 3CX Server

[Coinmaster]

Hello all,

I am a happy user of 3CX, which I have been using for some years now. First of all a sincere Thank You! To 3CX for this. This is the reason I have been telling about 3CX to my clients (although I am not a 3CX partner or anything).

Now, let’s get to the situation I am facing. All the technical details at the bottom of this post.

0. Problem Description​

Android 3CX App has issues connecting to the VPS. When opening the app, it takes quite a lot of time (a minute or so) in order to connect (green mark at top-right, show me the recent call list, etc). This issue happens ONLY when the device is on mobile data (Cosmote Greece). When on Wi-Fi, it is smooth sailing.

Troubleshooting the issue, I found out that the App times-out trying to connect via IPv6 and then falls back to IPv4. I made sure this theory is correct, by troubleshooting with Ping & Net android app. Indeed, I can not ping the IPv6 address of the VPS where 3CX is installed (request timeout). Although I have no issues pinging the IPv6 of other hosts (Hetzner, netcup, Contabo).

I have come up with the following possible solutions, but I am open to discuss any other possibility.

1. FQDN​

The FQDN has both AAAA and A records. Since IPv6 is preferred, 3CX App first tries IPv6 before falling back to IPv4. I could remove the AAAA record, but have no control over the FQDN (it is something.3cx.gr). I do not think there is a way to have my own FQDN with the License I have (so I could completely remote the AAAA record).

2. Disable IPv6 on the VPS?​

I am NOT a fan of disabling IPv6 and I would only consider this solution as a last resort. Moreover, I am not sure that even if disabling IPv6 on the VPS/3CX, that would eventually remove the AAAA record of the FQDN (if anyone know, please do say)

3. Talk with mobile service provider​

Unfortunately, mobile service providers in Greece have formed a cartel. Apart from the worst prices when inside a cartel, we also get the worst service! It is unthinkable to even be able to find a knowledgeable representative, to discuss about this issue. Let alone solve the problem

4. Try with different mobile service provider​

I could try a test, but I wouldn't actually want to change provider. This one is the least bad.

5. Change VPS?​

I consider it possible. But what is the correct course of actions?
I have read somewhere in the forum (sorry didn’t note the URL), that I first need to disconnect the FQDN within https://portal.3cx.com. Is this correct?

6. More questions about changing VPS:​

1. Are there any other considerations before starting the migration process?
2. Will I be able to transfer all data and license to the new VPS?
3. Will there be any License complications? (I am asking this, because there have been some changes in 3CX Licensing recently and maybe there is something I may need to pay attention to)

Technical Details​

1. 3CX Standard 4 SC, version 20.0 Update 5 (Built 551), Self Managed (Self Hosted) and I would like to keep it that way
2. VPS Provider: alphavps.com
3. 3CX Android App version 20.3.0

Please tell me if I have missed something.

 

[SteveITS]

> I can not ping the IPv6 address of the VPS where 3CX is installed

Ask your host if IPv6 is supposed to be pingable. While pinging is often allowed, that is not always the case. Try a traceroute also.

You should be able to back up and restore to a new install. You would not release your FQDN for this. A Pro license has a 6 hour TTL. I don't know about Free but I doubt it is shorter.

In Admin > Advanced > Network you could try unchecking "Automatically bind to IPv6 adapters. Requires SIP service restart" but I do not know if that would remove the AAAA record...I would think so. But you may need to wait the 6 hours, or query 3CX's name servers directly.

Can you find a location with IPv6 and try to open your web client URL? I'd wonder if the IPv6 address is set up correctly, allowed by provider's firewall, etc.

 

[Coinmaster]

Thank you Steve for your suggestions!
I'm sorry I didn't make it clear.. Using other networks as source (other hosts, or devices, or even the same mobile device connected to WiFi), I have no issues pinging the IPv6 of the VPS. Moreover, I can also telnet to open TCP ports of the VPS, using IPv6. For all I can tell, IPv6 of the VPS is working as expected.
Very usefull information the 6 hour TTL! Thanks! Yes, I could try unchecking "Automatically bind to IPv6 adapters..." and see what happens. Will try it tonight, so by tomorrow morning I should know ;-)

 

[Coinmaster]

I would like to add the following information, in the hope it will help others...

Unchecking Admin > Advanced > Network > "Automatically bind to IPv6 adapters" does not remove the AAAA record of the FQDN even after ~48 hours. So, in my case at least, this did not resolve my problem.

I managed to solve the problem, by disabling IPv6 on the Android Mobile APN like this:

• Open Settings: Go to the Settings app on your Android device.
• Network & Internet: Tap on "Network & Internet" or "Connections," depending on your device.
• Mobile Network: Select "Mobile network."
• Access Point Names: Tap on "Access Point Names." You might see a list of APNs.
• Select APN: Tap on the APN you are currently using. This will open the APN settings.
• APN Protocol: Look for the "APN protocol" field. Change it from "IPv4/IPv6" to "IPv4" only.
• Save Settings: Save the changes and exit the settings.
• Restart Your Device

Now, there are no delays in the 3CX App when using mobile data

 

[SteveITS]

I tend to forget since we use static IPs but there's a choice in the network settings whether the IP is static or dynamic. Even if it's a static IP try setting it to dynamic for a while, to help it update.