Troubleshooting the Issue of Domain Name Resolution Failure on Mobile Devices

The issue of domain name resolution failure on mobile devices has been reported by several users, typically in specific regions. The users are experiencing problems using the mobile app (both Android and iOS) and public account, but the issue resolves when switching to mobile network or using a different WiFi network. Based on error messages, the problem is identified as a DNS resolution failure. The users' WiFi devices are unable to perform DNS resolution, which is unusual for devices connected to the same WiFi network.

To troubleshoot the issue, several hypotheses are proposed:

* The users' DNS servers are modified to use a different DNS server (47.93.12.156), which is an Alibaba Cloud server. Testing by manually setting the DNS server on the users' devices confirms the problem. However, colleagues are unable to reproduce the issue, suggesting a relationship with different broadband settings.
* The users' devices are using local domain name resolution instead of the public DNS server.
* Another user experienced the issue one day but recovered after doing nothing the next day.

Potential explanations for the issue include:

* The users' devices are using a DNS server provided by the local internet service provider (ISP).
* The ISP may be blocking the educational platform, causing the issue.

The proposed solutions for the issue are:

* Integrating HTTPDNS into the app to resolve the DNS resolution failure.
* Limiting the public account to use public DNS servers or mobile network instead of WiFi.