Thank you guys, I solved that problem. For some reason my router's WiFi was blocking the bigger files to transfer, when I connected my Pi to it by the cable everything worked perfectly.

I bought a RPI3 today and started setting it up, the first thing I did was to enable the SSH connection, PuTTY worked perfectly, but when I tried to connect using WinSCP and FileZilla, they timed out. So I changed the default SFTP home directory in the "sshd_config" file and I was able connect, but ...