No internet after switch wlan <-> mobile connection using DNS-over-QUIC

[Morku]

Please answer the following questions for yourself before submitting an issue.

• [X] I am running the latest version
• [X] I checked the documentation and found no answer
• [X] I checked to make sure that this issue has not already been filed

AdGuard version

4.4.5

Tunnel mode

Split-Tunnel

Environment

- OS: 16.3
- Device and storage size: iPhone Xs Max, 64GB

What filters do you have enabled?

AdGuard Base filter, AdGuard Mobile Ads filter, AdGuard German filter, AdGuard Tracking Protection filter

Issue Details

1. Enable DNS protection
2. DNS Implementation: AdGuard, DNS Server: AdGuard DNS "not filtering" (DNS-over-QUIC)
3. Change your internet connection by e.g. disable WLAN for mobile connection
4. No more internet, because local VPN is "connecting ..." (Status: Verbinden ...) forever
5. To workaround -> En-/Disable flight mode until the next connection change appear

Expected Behavior

seamless transition from wlan<>mobile with directly connecting local VPN and no need to toogle flight mode

Screenshots

Video 1:

https://user-images.githubusercontent.com/6276915/216780300-d1e00c49-b15b-4a6f-89b9-802e92716e2e.mp4

Additional Information

When I use DNS-over-HTTPS I don't have that issue. VPN is connecting directly fine and so I don't miss a message when I walk around.

[ghost]

Possibly the same as #1958

[Morku]

Maybe. But I don't see in that report pointing to DNS-over-QUIC (DoQ). Even more, the user antplus says that DoH/DoT seems not related to his problem. However, myself I don't have an issue with DoH. It's all related to DoQ for me.

[Versty]

@Morku Hi! Does this issue reproduce every time when you switch from Wi-Fi to cellular? It so, please collect the debug logs and send it to our email.

Please follow the steps below:

1. Open Settings --> General --> Turn Advanced mode on --> Advanced settings --> Turn Debug logs switch on;
2. Reproduce the issue and remember the exact time when it happened;
3. Disable DNS protection
4. Open the settings --> Support --> Export logs;
5. System popup will be opened --> Choose "Mail" app;
6. Enter apple@adguard.com as a recipient;
7. Mention this issue number in the subject and add the time the issue was reproduced at.

[Morku]

Hi @Versty,

unfortunately it is a sporadic issue and I can't reproduce every time. But in past it was often enough to get really annoying. I have sent a Logfile to the Email.

[Morku]

Hi,

I was able to reproduce the issue once more and have sent another Logfile. This time able to follow your steps exactly (DNS protection off after repdroducing issue). Hopefully the Logfile will contain useful information.

[Versty]

@Morku Thanks, your logs have been received. We are investigating the depths.

[Versty]

@Morku We have found the cause. This is a bug, it will be fixed in the long term.

[Morku]

Glad you found the issue and I could help.