I am sending files over WAN from Ubuntu 8 to OSR 5.07 on regular basis without a problem using ftp and rsync.
Today I can not send anything bigger than ~1350 bytes, tried ftp, rsync, scp, it becomes frozen and I have to kill the process. Smaller files are sent without issue. Telnet and ssh connections are just fine, I can telnet and cat 10KB file to the screen without a problem.
Would appreciate any pointer where to start looking and fixing this weird problem.