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SFTP Connection Issue with Dropped VPN Connection

#1

Hi SFTP users and developers,

I would appreciate a hint on how to best debug this with ST4 and the SFTP plugin.

Situation is that I have remote machines in the company network that I need to access with VPN. VPN has a default timeout to automatically drop a connection after 48h. But also sometimes I have to drop the VPN connection. If such a VPN drop happens while I have an SFTP connection to a remote machine, SFTP cannot reconnect to the machine (either when saving a remote file or even reconnecting anew). I have to close ST4, restart it, and then reconnect.

I have tried to capture this in a debug file, but the debug log becomes rather large when monitoring the connection. When turning on debug logging when the problem happens, all I can see in the log file is this:

2025-08-18 20:11:17, SFTP: Starting Browse Path Thread from List
2025-08-18 20:11:17, SFTP: Waiting for previous thread
2025-08-18 20:11:17, SFTP: Beginning file transfer thread
2025-08-18 20:11:17, SFTP: Checking license key
2025-08-18 20:11:17, SFTP: Starting operation cwd
2025-08-18 20:11:17, SFTP: Finished operation cwd
2025-08-18 20:11:17, SFTP: Waiting for previous thread
2025-08-18 20:11:17, SFTP: Beginning file transfer thread
2025-08-18 20:11:17, SFTP: Checking license key
2025-08-18 20:11:17, SFTP: Starting operation list
2025-08-18 20:11:17, SFTP: Clearing keepalive
2025-08-18 20:11:17, SFTP Write:
    ls
2025-08-18 20:11:17, SFTP: Setting keepalive to 1755540706

In that state, I can still connect to another remote machine, but the original connection cannot be restored unless ST is restarted.

I wonder if this is something that would need to be fixed in my SSH configuration or if this is hinting at a potential quirk in SFTP.

Kind regards,
-michael

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