I tried it lots of ways. I'm using FireZilla Client.
----
Status: Resolving address of supertestwiki.vndv.com
Status: Connecting to 207.210.86.252:21...
Status: Connection established, waiting for welcome message...
Response: 220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
Response: 220-You are user number 44 of 250 allowed.
Response: 220-Local time is now 10:56. Server port: 21.
Response: 220-This is a private system - No anonymous login
Response: 220-IPv6 connections are also welcome on this server.
Response: 220 You will be disconnected after 2 minutes of inactivity.
Command: USER diligentterrier@vndv.com
Response: 331 User diligentterrier@vndv.com OK. Password required
Command: PASS *********
Response: 530 Login authentication failed
Error: Could not connect to server
----
Status: Resolving address of supertestwiki.vndv.com
Status: Connecting to 207.210.86.252:21...
Status: Connection established, waiting for welcome message...
Response: 220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
Response: 220-You are user number 50 of 250 allowed.
Response: 220-Local time is now 11:02. Server port: 21.
Response: 220-This is a private system - No anonymous login
Response: 220-IPv6 connections are also welcome on this server.
Response: 220 You will be disconnected after 2 minutes of inactivity.
Command: USER diligentterrier
Response: 331 User diligentterrier OK. Password required
Command: PASS *********
Response: 530 Login authentication failed
Error: Could not connect to server

a little help would be nice

Host: sitename.vndv.com (supertestwiki.vndv.com)
User: sitename (supertestwiki)
Password: *******
Port: 21

Still doesn't work:

Status: Resolving address of supertestwiki.vndv.com
Status: Connecting to 207.210.86.252:21...
Status: Connection established, waiting for welcome message...
Response: 220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
Response: 220-You are user number 63 of 250 allowed.
Response: 220-Local time is now 05:59. Server port: 21.
Response: 220-This is a private system - No anonymous login
Response: 220-IPv6 connections are also welcome on this server.
Response: 220 You will be disconnected after 2 minutes of inactivity.
Command: USER supertestwiki
Response: 331 User supertestwiki OK. Password required
Command: PASS *********
Error: Connection timed out
Error: Could not connect to server
Status: Waiting to retry...
Status: Resolving address of supertestwiki.vndv.com
Status: Connecting to 207.210.86.252:21...
Status: Connection established, waiting for welcome message...
Response: 220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
Response: 220-You are user number 59 of 250 allowed.
Response: 220-Local time is now 06:00. Server port: 21.
Response: 220-This is a private system - No anonymous login
Response: 220-IPv6 connections are also welcome on this server.
Response: 220 You will be disconnected after 2 minutes of inactivity.
Command: USER supertestwiki
Response: 331 User supertestwiki OK. Password required
Command: PASS *********
Error: Connection timed out
Error: Could not connect to server
Status: Waiting to retry...
Status: Resolving address of supertestwiki.vndv.com
Status: Connecting to 207.210.86.252:21...
Status: Connection established, waiting for welcome message...
Response: 220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
Response: 220-You are user number 65 of 250 allowed.
Response: 220-Local time is now 06:00. Server port: 21.
Response: 220-This is a private system - No anonymous login
Response: 220-IPv6 connections are also welcome on this server.
Response: 220 You will be disconnected after 2 minutes of inactivity.
Command: USER supertestwiki
Response: 331 User supertestwiki OK. Password required
Command: PASS *********
Error: Connection timed out
Error: Could not connect to server

No, it seems working for you since you no longer get the "530 Login authentication failed". It just keeps on timing out on you. I don't know how to solve that. Sorry.

set the FTP clients timeout to a longer time. It's probably currently set at 30 seoconds.

Any other tips?

go to Edit>settings>transfers, and where it says: timeout limit, put "0" in the box click ok/apply and connect again and you wont timeout

Yep, actually is not working fine. A lot of inconsistent errors and inestability.... hope admins make something to fix it soon