Automated queries error for longer prompt calling gemini-3.1-flash-image-preview

I am calling gemini-3.1-flash-image-preview from my server (ip = …51), and when the prompt is long, i got the error (below), but when the prompt is very simple, there is no error!

However, when I tested from my home computer, both long and short prompt get good response. What should I do?

Sorry... body { font-family: verdana, arial, sans-serif; background-color: #fff; color: #000; }
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Found a fix: need to add Expect: to the curl headers