One unexpected challenge while building PayTrack this week:

The backend suddenly stopped communicating with Supabase even though the application code was completely correct.

After hours of debugging Flask configs, API requests, credentials, CORS, and network calls, the actual issue turned out to be DNS routing from the ISP itself.

The backend simply could not properly reach Supabase servers.

Changing DNS settings to Google/Cloudflare fixed the issue instantly.

Interesting reminder that software debugging is often larger than the application code itself. Infrastructure, networking, DNS, and external services can quietly become the real source of failure.