Cobian Reflector keeps disconnecting from FTP server

[GabrielAlmeida]

Hello!

Recently, I managed to create a FTP server with DNS and SSL, and now I want to set it as the destination for my backups. The server itself is working fine: in Filezilla, the server connects and the connection keeps active until I disconnect. In Cobian Reflector 1.1.3 tough, the connection test works just fine (Cobian connects, create the test file, then disconnects), but when I run the backup, the connection constantly drops randomly, and thus I get a backup with errors. That's the log I get from Cobian:

2022-08-19 14:48:40 Connecting to [my server]...
2022-08-19 14:48:41 Connected to [my server].
2022-08-19 14:48:41 Logged in into the remote server.
2022-08-19 14:48:41 The remote directory "/Thunderbird 2022-08-19 14;48;41" has been successfully created.
2022-08-19 14:48:41 Uploading the directory "C:\Users\Raca\AppData\Roaming\Thunderbird" to "/Thunderbird 2022-08-19 14;48;41"...
2022-08-19 14:48:42 The server has disconnected. Reconnecting...
2022-08-19 14:48:42 Connecting to [my server]...
2022-08-19 14:48:42 Connected to [my server].
2022-08-19 14:48:42 Logged in into the remote server.
2022-08-19 14:48:44 The server has disconnected. Reconnecting...
2022-08-19 14:48:44 Connecting to [my server]...
2022-08-19 14:48:44 Connected to [my server].
2022-08-19 14:48:44 Logged in into the remote server.

This keeps going until some operation isn't able to execute:

2022-08-19 08:51:29 O servidor foi desconectado. Reconectando ...
2022-08-19 08:51:29 Conectando-se a [my server] ...
2022-08-19 08:51:29 Conectado a [my server].
2022-08-19 08:51:29 Conectado ao servidor remoto.
ERR 2022-08-19 08:51:32 Não foi possível criar o diretório remoto [directory]: The FTP client has not yet connected to the server. The requested action cannot be performed until after a connection has been established.
ERR 2022-08-19 08:51:32 Não foi possível criar o diretório remoto [directory]: The FTP client has not yet connected to the server. The requested action cannot be performed until after a connection has been established.
ERR 2022-08-19 08:51:32 Não foi possível criar o diretório remoto [directory]: The FTP client has not yet connected to the server. The requested action cannot be performed until after a connection has been established.
ERR 2022-08-19 08:51:32 Não foi possível criar o diretório remoto [directory]: The FTP client has not yet connected to the server. The requested action cannot be performed until after a connection has been established.

Sometimes I get this error as well:

2022-08-19 08:51:58 O servidor foi desconectado. Reconectando ...
2022-08-19 08:51:58 Conectando-se a [my server] ...
2022-08-19 08:51:58 Conectado a [my server].
2022-08-19 08:51:58 Conectado ao servidor remoto.
ERR 2022-08-19 08:52:03 Não foi possível criar o diretório remoto [directory]: Control channel unexpectedly closed ('' read so far)
ERR 2022-08-19 08:52:03 Não foi possível criar o diretório remoto [directory]: The FTP client has not yet connected to the server. The requested action cannot be performed until after a connection has been established.
ERR 2022-08-19 08:52:03 Não foi possível criar o diretório remoto [directory]: The FTP client has not yet connected to the server. The requested action cannot be performed until after a connection has been established.
2022-08-19 08:52:03 O servidor foi desconectado. Reconectando ...
2022-08-19 08:52:03 Conectando-se a [my server]: 21 ...
2022-08-19 08:52:03 Conectado a [my server]: 21.
2022-08-19 08:52:03 Conectado ao servidor remoto.

This only happens when the connection is using SSL (passive mode, explicit, SSL certificate from NoIp and generated with OpenSSL). I tested it with plain FTP, and the backup runs perfect with no errors.

I'm a total noob in all of this, and I am figuring things out as I go. Does anyone have some idea of what is causing this? I have this connection problem only on Cobian Reflector, so my guess is that I'm configuring something wrong or it is a problem with the FTP service of Cobian itself.

[cobian]

if you disable your firewall (temporarily) does it work then?

[GabrielAlmeida]

No, same thing happens... Connection unstable with SSL, works fine with plain FTP

[cobian]

What kind of server is this?

[fledorze]

Hello
I have the same behaviour for only one Windows host in the same LAN than other for which it is working fine with FTPS Explicite (Our NAS QNAP QTS does support only this mode or Insecure FTP) :
Connection is fine :
2024-04-28 00:09:01 Backing up the task "To_Nas"
2024-04-28 00:09:01 Applying the parameters to the task "To_Nas" (if any).
2024-04-28 00:09:01 Requesting the creation of a Volume Shadow Copy image for the source...
2024-04-28 00:09:02 The Volume Shadow Copy image has been successfully created.
2024-04-28 00:09:02 Starting the copy. The user running the task is: Système
2024-04-28 00:09:02 Connecting to tbrd.vic.verkor.com:21...
2024-04-28 00:09:17 Connected to tbrd.vic.verkor.com:21.
2024-04-28 00:09:18 Logged in into the remote server.
2024-04-28 00:09:18 Uploading the directory "C:\Users\Digatron\Documents\Data" to "/tbrd/Raw_Backup/DIGATRON/pc-digatron/Data"...


Then first error log is :
ERR 2024-04-28 00:09:27 Couldn't change the remote directory to "/tbrd/Raw_Backup/DIGATRON/pc-digatron/Data/Electrode/231121- PVDF Solef 6020 (Vx)/451-500": Control channel unexpectedly closed ('' read so far)

Then :
ERR 2024-04-28 00:09:27 Couldn't create the remote directory "/tbrd/Raw_Backup/DIGATRON/pc-digatron/Data/Electrode/231121- PVDF Solef 6020 (Vx)/451-500": The FTP client has not yet connected to the server. The requested action cannot be performed until after a connection has been established.

No problem with
- when I set unsecure mode
- when I set other source Folder of the same host => It is not a firewall problem
- when I set "C:\Users\Digatron\Documents\Data\Electrode"

Could it be that the folder name itself is problematic ?
Very strange
Thx

[cobian]

You never know with NASes. I worked with a nas that didn't accepted semicolons in the file names...

[fledorze]

We rechecked in Firewall logs, no trace of this disconnection.
Same thing in NAS logs.
I'll keep unsecured mode for this server only and will ask to the team in charge of characterization software installed on it to have more "reliable" folder names.
Some folder names are crazy, with for example temperature value of the test with the ° symbol .
Thank you for your help.

[cobian]