Hello Julien,
Sorry to see you have not had an answer to your question. I haven't used WiFi in Rojales but the bars/ cafe's & restaurants that do have WiFi will generally have a label on their window or door saying 'WiFi Here'.
I would be very surprised if there wasn't anywhere in Rojales with WiFi as it's becoming very popular and helps to get customers through the door.
Hopefully someone else may know of somewhere but if you find any places when you are there, please let us know on the forum. It's always good to know of more places with WiFi.
Jan.