Hi Antonio - I can't think of anything relevant that has changed on the Savannah side.
First, you might try simply "ssh svn.savannah.gnu.org". You should get a message from the host about "Interactive shell login is not possible"; if instead you get "Permission denied", presumably ssh is failing in general. Running ssh -vvv might produce more clues. (In the past, the problem has very often been that the ssh key you are using is not registered in your savannah account.) If none of that helps, you might try doing a new checkout with the command as given on https://savannah.gnu.org/svn/?group=chess? (That would distinguish problems with your existing checkout from svn in general.) Best, Karl