TWSD-1357 FTPS Upload Fails with “426 Failure writing network stream”

Review Request #1215 — Created Dec. 8, 2025 and submitted Dec. 10, 2025, 1:49 a.m.

Information
Owner:	weikai
Repository:	APV10
Branch:
Bugs:	rel_apv_10_7, rel_apv_10_7_3, rel_apv_10_7_3_25_HSOL, rel_apv_10_7_3_26_HSOL, rel_apv_10_7_3_29_HSOL, rel_apv_10_7_4
Depends On:
Reviewers
Groups:
People:	kevin.poh, mingji, peteryeh

Description

TCP timeout setting command: system tune tcpidle <timeout>

FTP(S) SLB (Server Load Balancer) stops transmission when file download/upload exceeds the timeout.
The error "426 Failure writing network stream" occurs when the time reaches two times the timeout value.

Testing Done

The minimum value for the command system tune tcpidle <timeout> is 60 (seconds).
Testing the results usually takes 1-2 minutes.

Accelerating the Test
To speed up the test, you can modify the timeout directly as root. 
The example sets the value to 10 seconds (10000 milliseconds).
Note: Adjust this value based on your environment; setting it too short may cause timeouts even during login.
1. Log in with root privileges.
2. Execute the command: /ca/bin/u_sysctl net.inet.clicktcp.idle_timeout=10000

Requirement for Each Transfer:
- Each file transfer (upload or download) must exceed the configured timeout duration.

Test Procedure:
1. Upload a file 10 times.
2. Download a file 10 times.