slow ftp speeds w time capsule

hi.
just bought a new time capsule which i have setup wired to my modem (which is in bridge mode). the tc is therefore acting as my router.

since setting it up i have terrible speeds from my ftp server... seems like i have a port forwarding problem and can't work out how to fix it! i've tried a few different online tutorials for port forwarding

i briefly tried using the time capsule in bridge mode and it completely fixed the problem. any ideas??

cheers