Filezilla getting connections rejected

[#1]

I'm using filezilla to upload simple photo galleries.
During the upload, I frequently get the following in the log. I have restricted the number of connections in filezilla to 4. Sometimes I also get some of the files failing to upload.
Any ideas?

Response: 220 Plus.Net FTP Server #4 ready
Command: USER collinet
Response: 331 Password required for collinet.
Command: PASS ********
Response: 331 Password required for collinet.
Command: PASS ********
Response: 530 Sorry, the maximum number of clients (4) for this user are already connected.
Error: Could not connect to server

[#2]

Does it work if you untick the maximum connections setting? That's how it is set for me, which I presume is the default.

[#3]

Makes no difference - ticked or unticked.

[#4]

Try limiting the connections to 1 or 2. Sometimes the far end takes a while to clear previous connections, especially if they have not closed properly. By limiting to 1 or 2 you don't reach the connection limit (which is at the plusnet end) and gives the server more time to clear any older connections.