Welcome to the Rogers Community Forums! 🙂
Thank you for posting your query in the Community. I believe by "open network" you mean the Guest Network. It appears to be unsecured however, it would prompt for the Guest password once you open a web browser.
You can log into the modem and disable your Guest Network from the Wireless/Guest Network menu. You can follow the walkthrough to log into the modem and navigate to Guest Network to disable it.