FTP ls and dir hangs

Hi, My script suddenly failed 2 weeks ago after working for years. ‘ls’ command hangs after the script loggin anonymously. This script was written in c shell. I also have another script written in perl and use the Net::ftp module to ftp the same exact site and ‘ls’ without any problem. Could someone please tell me what suddenly went wrong and what can I do to make my script work again? Thank you very much!!!