Thank you for contacting Lennar Home Community.
Hope you are doing well!!!
As per the case description, I could understand that your RUCKUS setup is not working after connecting a new modem.
Yes, you need Router or Modem-Router combo from your ISP (Internet Service Provider) connected to the ICX-7150-C12P switch. And from the 12 Switch ports, you could connect your devices such as Access Points, smart devices, wired ethernet cables for your laptop/PC, etc., It doesn’t work only with Modem. The connection must be from a Router or Modem-Router combo device. RUCKUS only has a Switch and Access Point in the Lennar home setup.
Please refer to the short guide link below about how to connect the devices as a reference:
Most common Setups for Lennar homes users:
Please let me know if you have any queries in this regard.
Thank you again.
Lennar Home Community.