SOLVED FTP upload problem

Hello,
I have a problem with files uploading via FTP to my Server. Searched this forum, but didn't find any solution to my problem unfortunat.
The problem started after migrating to CentOS 7; using Pure-FTP, EA4, CSF.

I followed instructions in: "How to Enable FTP Passive Mode" at cPanel KB:
-passive ports range is set in pure-ftpd.conf
-same range is opened in CSF firewall
-using passive mode in FTP over Port 21

Symptoms:
-can connect via FTP to any web account
-can see listing(s), can delete/rename files/folders
-can download any files with no problem

-sometimes can upload one single file or 2-3 files, but when it comes to upload in bulk/folder(s) FTP client just freezes and won't upload at all or get message after a while 'File transfer failed' -> FTP reconnects and start over, then hangs.

Any suggestions what is wrong here?

p.s: can connect via the same FTP client to another Server (from my VPS provider) and upload/download without any problem

Appreciate any help, thank you.

//A

 

Thank you for answering,
I'm using FTP plain connection (passive mode), worked well over many years while we were on CL5 server, tried with both Filezilla and FlashFXP.

Is it wise and safe to disable CSF firewall on Live Server? even for a short period of time to test?

 

Thank you,
I saw that thread before I posted my question. I searched indeed as much I could about our FTP problem, but couldn't really find a satisfying solution, yet.. I can confirm that a range of 'passive ports' is set for Pure-FTP and is opened in CSF firewall.

As I can verify for the moment the problem with FTP uploading still not fully resolved, but this is what we have right now:
-uploading via FTP for instance working better today (from same IP, no changes made to CSF), e.g we were able to upload multiple files, have tested with several accounts on that VPS. However once a while FTP still pauses -> uploading rate drops to Zero -> and finally gives us 'Transfer failed', but eventually uploads files to Server. So, it does work in general, but something still causing those random 'Transfer failed' that was never experienced earlier.

-I also tested to upload via FTP to the VPS by simply connecting my laptop via mobile phone, e.g another IP provider. Such test confirmed, that there is no problem to upload to Server - tested with many different files/folders, normal behavior.

-I can also upload via same FTP client, from same IP which presumably have issues with new VPS to another Server from my hosting provider, and according to them they do NOT even use 'passive ports' there ?

Does all above clarify anything or hopefully narrowing to some specific problem?
could it be some Server / CSF settings that causing such troubles? our IP-nr is white-listed in WHM and I couldn't find it anywhere in IP tables, it doesn't look like IP-block since we can reach WHM/cPanel/websites/mails at all time.

Appreciate any help!

 

My hope was to get some answers to such strange specific FTP problem by describing symptoms of the problem ) Unfortunately, we cannot grant full access to our VPS, our hosting provider can also do a troubleshooting if it comes to that.
Seems we just have to continue doing more tests and try to find a solution.
Thank you for your help with this question.

 

Just a closure on this topic..
our problem with slow or none-responding FTP service from particular IP was Router related:
after replacing router + re-configuring network problem was solved, so it was not VPS related.