FTP has mysteriously stopped working

For some reason, FTP has suddenly stopped working on my MacBook Pro. I've tried with Cyberduck, Firefox and Camino. I've tried rebooting, and I've tried restarting the modem and router (a Time Capsule).

I know there's nothing wrong with the remote server, *because I can use FTP fine on my MacBook on the same wifi network.*

With Firefox I get the error:

+426 Transfer aborted. Data connection closed.+

With Cyberduck I get the error:

+Read timed out.+

The full log for Cyberduck is:

+220 ProFTPD 1.3.0a Server ready.+
+USER tester+
+331 Password required for tester.+
+PASS ******+
+230 User tester logged in.+
FEAT
211-Features:
MDTM
+REST STREAM+
SIZE
+AUTH TLS+
PBSZ
PROT
+211 End+
+CWD /+
+250 CWD command successful+
+TYPE I+
+200 Type set to I+
PASV
+227 Entering Passive Mode (209,240,132,53,7,89).+
+RETR FILE.zip+
+150 Opening BINARY mode data connection for FILE.zip (36911497 bytes)+
QUIT
+220 ProFTPD 1.3.0a Server ready.+
+USER tester+
+331 Password required for tester.+
+PASS ******+
+230 User tester logged in.+
FEAT
211-Features:
MDTM
+REST STREAM+
SIZE
+AUTH TLS+
PBSZ
PROT
+211 End+
+CWD /+
+250 CWD command successful+
+TYPE I+
+200 Type set to I+
PASV
+227 Entering Passive Mode (209,240,132,53,9,234).+
+RETR FILE.zip+
+150 Opening BINARY mode data connection for FILE.zip (36911497 bytes)+
QUIT