Update — October 24, 2026 We have upgraded ProfiMusic from Expo SDK 57 to Expo SDK 58.0.19 (React Native 0.88.0) and installed a signed Release build on the physical iPhone 15 Pro running iOS 27.0.1. Unfortunately, the issue persists with exactly the same symptoms. The application still hangs during login, as it did with SDK 57. The upgrade was completed successfully, with the production API endpoint and signing configuration preserved. Additionally, our independent native Swift application using URLSession reproduced network timeouts without involving React Native or Expo. In one test, 13 consecutive requests timed out with error NSURLErrorDomain -1001, without receiving an HTTP response. Their request IDs were not found in the corresponding Nginx or Fastify logs. At this point, upgrading Expo has not resolved the issue. Could this behavior be related to changes in URLSession, CFNetwork, TLS, or network path handling on newer iOS versions? What additional diagnostics would help identify the root cause? Any guidance from Apple networking engineers or developers who have encountered similar behavior would be greatly appreciated.