By default - for whatever bizarre reason - sshd only listens to the usb0 interface. In /lib/systemd/system/sshd.socket you will find the following:
ExecStartPre=/bin/mkdir -p /var/run/sshd
# restrict access to wired access for security reasons
# comment this line to remove restriction
Comment out the BindToDevice (or nuke the line alltogether), reboot and sshd will listen to the WiFi interface as well. You might also have to set a password for root (I am not sure if that is required but it's a good thing anyway).
//Lars Boegild Thomsen
Edison doesn't allow ssh to via other network devices until you set up a password in configure_edison. If they didn't do that, everyone on your wifi network (and possibly the wider Internet) could ssh into your Edison as root.
Once you set a root password in configure_edison, you can ssh in from any attached network. No need to mess with config files manually.