Hi. I would like to work on this issue, please assign it to me.

Hi @GourabSanyal! How is it going? I had problems with IPv6, too, and admins found that the server has AAAA DNS record, but doesn't accept IPv6 connections to the running Mattermost server. One colleague mentioned, that browsers solve this via the Happy Eyeballs algorithm (see https://datatracker.ietf.org/doc/html/rfc8305) – Mattermost works in the web browser on the same device and network. Maybe it could be done here using it, too (in the case you haven't started yet or you haven't already found a better solution).

Hi @ceskyDJ , I've created something and will soon submit a PR for it. In the meantime, could you recommend a good testing approach? Thanks!

I propose these test cases based on my problem:

TC 1: Adding a server instance to the app without IPv6 connectivity properly set up

Setup:

1. Setup Mattermost server available via hostname. Create A and AAAA records for that hostname. Limit server to listen to IPv4 only.
2. Install Mattermost mobile app on Android phone (Samsung Galaxy S22, Android 14 in my case).
3. Connect your phone to some dual stack (IPv4 + IPv6) network (Wi-fi or cellular network).

Exercise:
3. Open the Mattermost mobile app and try to add the created Mattermost server instance via hostname.

Verify:
4. Check if the Mattermost server instance is successfully added to the mobile app.

Teardown:
5. Uninstall the Mattermost server instance and the mobile app.

TC 2: Connecting to the Mattermost server instance from the mobile app (already added)

Setup:

1. Setup Mattermost server available via hostname. Create A and AAAA records for that hostname. Limit server to listen to IPv4 only.
2. Install Mattermost mobile app on Android phone (Samsung Galaxy S22, Android 14 in my case).
3. Connect your phone to some IPv4-only network.
4. Add the Mattermost server instance.
5. Connect your phone to some dual stack (IPv4 + IPv6) network (Wi-fi or cellular network).

Exercise:
3. Open the Mattermost mobile app, select the tested Mattermost server instance.

Verify:
4. Check if the app successfully connects to the server instance and synchronize messages.

Teardown:
5. Uninstall the Mattermost server instance and the mobile app.

I am also facing the same problem with my server, have you guys fixed this problem, please let me know the solution if any. Thanks a lot

I've created something and will soon submit a PR for it. In the meantime, could you recommend a good testing approach? Thanks!

@GourabSanyal did you ever push your changes anywhere? I'd be curious to see how you addressed the issue.

To add some more detail, I'm encountering this issue on my Android phone (Pixel 8a) as is another Android user on my server. The server is not available over IPv6 and I do not have and AAAA or similar DNS records. The issue only manifests when on mobile data as opposed to Wi-Fi. When on mobile data the phone is using IPv6. The Mattermost app is completely unable to connect to the server, it says "The server is not reachable". However accessing the Mattermost instance in a browser on the same phone works fine.

The following are screenshots from test-ipv6.com. Perhaps it is relevant that the DNS server of my mobile service is not accessible over IPv6:

I've created something and will soon submit a PR for it. In the meantime, could you recommend a good testing approach? Thanks!

@GourabSanyal did you ever push your changes anywhere? I'd be curious to see how you addressed the issue.

I stopped working on it way back. I hardly remember anything about solving this at this point, I'd request the maintainer to unassign me.

I recently experienced this with mattermost and also one of my react native app. I am actually testing this solution right now. Just waiting for android approvers to approve my app and I was wondering if I can create a PR for mattermost if this works for me?

I can connect through mattermost and my other app when I'm in wifi but if I am using my mobile data, it takes soooo slow. I can use the browser just fine.

I recently experienced this with mattermost and also one of my react native app. I am actually testing this solution right now. Just waiting for android approvers to approve my app and I was wondering if I can create a PR for mattermost if this works for me?

I can connect through mattermost and my other app when I'm in wifi but if I am using my mobile data, it takes soooo slow. I can use the browser just fine.

Just giving update that the link I shared fixed my app problem.

@rossjackson Thanks for the hint!
So the solution is to update okhttp3 to 5.0.0?

@rossjackson Thanks for the hint! So the solution is to update okhttp3 to 5.0.0?

Yes! That did the trick for my app! I can't wait for this fix because ive been using the PWA 😭😭

Went ahead and opened a PR because I can't stand the PWA version. I want the mobile app!