I have recently installed DD-WRT on my D-Link DIR-615 router (rev. D3). Everything seems fine but I cannot connect to some (most) FTP servers anymore. Any ideas what can cause this issue?
Passive/active doesn't make a difference.
I've discovered something interesting. I've set up a port range forwarding
1024-65535 | Both | 192.168.1.131 for the testing purposes. After that I have enabled or disabled (it doesn't really matters it seems) the UPnP service and it let me connect to FTP but just for a few seconds.