Hi Roger,

It sounds like you are hitting a known bottleneck with high-throughput ingestion over public TCP proxies. When moving multi-gigabyte files, public-facing TCP proxies are prone to packet loss, timeout variations, and MTU (Maximum Transmission Unit) fragmentation, which explains the "unexpectedly closed" SSL connections and gzip stream corruption you're seeing.

To answer your specific questions:

Can the proxy be configured? Generally, no. The TCP proxy is a shared infrastructure component meant for intermittent connections, not sustained, high-throughput ETL (Extract, Transform, Load) tasks. There are no user-accessible "knobs" to adjust its internal timeout or SSL buffer behavior.

Is there a way to bypass it? Yes, this is the most critical part of your solution. Because the proxy is the source of the instability, you want to eliminate the "middleman."

Would moving the job inside Railway help? Yes, absolutely. This is the recommended architectural pattern for your workload. By running your ingestion job inside the same Railway project (as a separate Service or a Cron Job), you can communicate with your PostgreSQL service via the Private Networking hostname (postgres-8ndh.railway.internal:5432).

Recommended Path Forward:

Move the compute to the data: Stop attempting to stream 11GB files over the public internet. Instead, package your ingestion script into a simple container (Docker-based) and deploy it as a "Service" or "Cron Job" within your Railway project.

Utilize Internal Networking: By using the .railway.internal hostname, your traffic never touches the public TCP proxy. It stays entirely within Railway’s internal software-defined network. This eliminates the proxy as a point of failure and provides a much higher, stable throughput with zero SSL/TCP fragmentation issues.

Data Staging: If you need to get the files into that environment, upload them to an S3-compatible bucket (like R2, AWS S3, or a Railway Volume if persistent storage is required) and have your internal service pull from there.

AI-assisted answer. I tested only a small synthetic local gzip file; I have not tested or accessed your Railway service.

The first useful split is download/decompression versus database ingestion. Your description says the gzip is downloaded to local SSD before import. Capture the complete traceback and stage for each failure. If reading that completed local file fails before any SQL is sent, investigate the download/file-writing stage first; that observation alone does not establish PostgreSQL proxy corruption.

My offline test created a valid 1,000-row synthetic gzip and verified its restored SHA-256. Removing only its final 8 bytes reproduced exactly EOFError: Compressed file ended before the end-of-stream marker was reached. This demonstrates a truncated-file failure, not the cause of your production failure. Python documents EOF errors for invalid gzip data. Python gzip

For your five questions:

1. Large transfers/configuration: First finish and close each download, validate the gzip by reading it fully, and compare source checksums/expected lengths where available. Keep incomplete downloads under a temporary name and retain validated inputs until import has committed and been verified. Record download bytes, decompression result and import result separately. This provides evidence before changing infrastructure.
2. Timeout/SSL controls: Railway's TCP Proxy documentation describes the public endpoint and target port; I cannot identify a documented user setting that would fix these errors. pool_recycle=280 replaces aged connections on their next checkout, not while they are held by an import. pool_pre_ping=True detects stale connections at checkout but cannot rescue a connection lost mid-transaction. Recover by retrying the entire affected transaction with a duplicate-safe import/checkpoint design. TCP Proxy, SQLAlchemy disconnect handling
3. External bypass: A custom CNAME still targets the same TCP proxy. Railway documents a separate private project route for services in the same project environment; that hostname is not a direct route from your local Mac. I would not promise an undocumented direct/VPN bypass. TCP Proxy, PostgreSQL connections
4. Known issue: These messages do not establish a known Railway proxy defect. Correlate failure timestamps with PostgreSQL/service logs and resource use, and provide a minimal failing input plus redacted downloader/import code and traceback. Keep download failures distinct from DB disconnects.
5. Move ingestion inside Railway: Using a worker in the same project environment and the private database endpoint removes the public TCP proxy from that DB connection. It is a useful comparison, but cannot repair an already incomplete gzip or guarantee that SSL/disconnect failures disappear. Compare the same validated input and bounded import batch on both routes before drawing a conclusion. Railway PostgreSQL, Private networking

The fastest next evidence is one failing file's completed-download length/checksum, a full gzip validation result, and the exact stage/traceback. That will determine whether to investigate source downloads, importer behavior or the database path.