Solved 3CX backups to FTP server keep failing for different clients

[SuperTima]

We have a few 3CX servers (all are v. 18 hosted on Amazon Lightsail servers) which would not upload the backups to our FTP server.
1) The FTP credentials are tested and confirmed working for those clients which can't finish the backup.
2) The FTP server is our on-prem Windows Server 2016 Standard with FileZilla Server instaled.
3) In the FileZilla logs we can see that the 3CX server establishes the FTP connection and gets the directory list, then disconnects with the following messages: "150 Opening data channel for file download from server of "/3CXScheduledBackup.2.zip" and then 426 Connection closed; aborted transfer of "/3CXScheduledBackup.2.zip"
4) Other 3CX servers upload their backups to the same FTP server with no issues.
5) Folder permissions on the FTP server have been revised and confirmed to be correct.
6) The backups are not protected with a password.
7) The backups do not include recordings or any other media files.
6) Local 3CX backups run normally.

This is what we get in the emails which are sent to us in the end of which backup:


Please share any ideas as I am pulling my hair out already

Thanks!

 

[ChrisC_3CX]

To first confirm a few things and get a bit more information:

• I know you've already mentioned that other PBX's work on the same FTP server, but could you confirm you followed this guide to configure the FTP server: https://www.3cx.com/docs/ftp-server-pbx-backups-windows/

• Are you using different FTP users per PBX?

• Are scheduled backups of different PBX's overlapping? If yes, could you arrange the times so they don't?

• Do manual backups work?

• What exact version are the affected PBXs? Check under "Dashboard >> Information >> Version/License"?

• Are ALL Lightsail PBX's affected? Do you have any firewall restrictions on the FTP server end that may be related such as geolocation restrictions?

EDIT:

• Also, check if your FTP server (FileZilla in this case) has a "simultaneous connection limit". If yes, try increasing the limit or better yet, lift the restriction completely and test again.

 

[SuperTima]

Hi Chris,
Thanks for your reply.
I found that our FTP server had different ports configured for data transfer - once I changed them back to the default range (10100 - 10199), the backups started working.
It is very strange as the other FTP connections (not from 3CX servers only) were working fine.

I will see how it goes for the next 5-6 days - we might find another 3CX server failing to upload backups, who knows

Thanks for your help!
Tim.

PS: answering your questions just in case:

• Are you using different FTP users per PBX?

Yes, they are all different.

• Are scheduled backups of different PBX's overlapping? If yes, could you arrange the times so they don't?

No overlaps.

• Do manual backups work?

They do.

• What exact version are the affected PBXs? Check under "Dashboard >> Information >> Version/License"?

18th.

• Are ALL Lightsail PBX's affected?

Not all of them (and that was the confusing bit).

 

[ChrisC_3CX]

I found that our FTP server had different ports configured for data transfer - once I changed them back to the default range (10100 - 10199), the backups started working.

Regardless if you use the default range or not, it should've worked if you used a port range that is not used for anything else and is that is also configured on the FTP's network firewall.

In any case, I'm glad to see you got this working again!

Please feel free to start a new thread should anything else come up!