If the Rachio is still watering on schedule, then only the Wi-Fi is out. If it had Ethernet then you could regain control it with that; so Ethernet is also be a backup to the Wi-Fi (and vice versa).
$250 for a device by a company to cheap to install a $3 Ethernet connection, they want you to buy more of their devices to make up for sub-par hardware.
I would love to install a Rachio, but I simply must have Ethernet.