WTelegramClient: Intermittent Auth_SentCode success — code arrives "via App" but is missing after periods of inactivity

1 day ago 1
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I am using WTelegramClient in a C# / .NET 9 environment to manage multiple user sessions (userbots). I am encountering a strange, intermittent issue with the login flow that I can't pin down.

The Scenario:

Sometimes it works perfectly: The client calls LoginUserIfNeeded, Telegram returns Auth_SentCode (sent via App), and the code arrives instantly in the user's official Telegram app.

The "Inactivity" Failure: After a few hours of bot inactivity or a service restart, the code stops arriving. The library still logs a successful → Auth_SentCode #17CC (sent via App), but the official Telegram client receives nothing.

Recovery: After waiting several hours (e.g., until the next afternoon), it suddenly starts working again without changes.

Technical Details:

No Errors: There are absolutely no FLOOD_WAIT_X or RpcException errors in the logs.

Log Output:

2026-03-13 18:54:46Z → Auth_SentCode #F96AA A verification code has been sent via App

What I've Observed: Since the library reports the code was sent successfully, it seems the request is valid, but the delivery is swallowed by Telegram.

Is there a known "silent" throttle for 3rd-party clients that can trigger this behaivour?

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