I have a Raspberry Pi 3, which I have been running headless with Raspbian Jessie. Recently I flashed Stretch to my SD card, but when I boot that on my Pi, I can't connect to it over SSH. A little research tells me that Stretch doesn't have SSH enabled by default, so some changes must be made to the boot partition. I tried saving a blank file titled ssh and another file titled wpa_supplicant.conf, containing the code shown below, to the boot partition however this still doesn't work. When I boot this on my Pi it still fails to connect over SSH and doesn't appear on scans of the network. If I plug the SD card back into my laptop, the two files I saved to it are gone. What should I do?
country=GB
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
ssid="Network SSID"
scan_ssid=1
psk="Password"
key_mgmt=WPA-PSK
}
network={
ssid="Dummy SSID"
scan_ssid=1
psk="Dummy Password"
key_mgmt=WPA-PSK
}