Zero byte file freeze FTP transfer

I made backup of my FTP server. When I upload files to FTP to another directory, I notice that zero byte file makes FTP transfer freeze. I have problem just with one server, but it's our company main virtual server and it's not cheap hosting.

"150 Opening BINARY mode data connection for 'zerobyte.txt'" - that is everything I see in log. Next is "User Aborted Transfer" (when I press "Abort").

I checked with FileZilla and is working. I was trying passive and active transfer in DO - no difference.

Which server software is it running?

Is there a way we could access the same server for testing, maybe with a guest account?

I can create that account. Give me possibility to send you private message or other type of private communication.

PS. Now I test closely and it's work bad only when I enable active mode (disable passive). On other server sometimes it works bad too (rarely), but on main server - it's easy to reproduce.

Did you try active mode with another client in case it's the same?

Hmmm, FileZilla can't even get directory listing from this server in active mode. Ok, something may be wrong not related to Opus. Sorry for not enough testing before report.