There is no need to replace the Switch, If you have confirmed that the Connection in your ISP router works fine and the only affected are the devices connected to the ICX7150 Switch, including the access points,it looks like your Switch (ICX7150 Switch) may be booting from the wrong partition, let me add the guide to fix the issue.
Note: if you have access to the Unleashed Dashboard and the Switch can be seen from there, it may look like the following image, ICX7150-C12-Router instead of ICX7150-C12-Switch, now before starting the steps of the guide, I will advise you to cable the computer directly to the Switch since you will have better connectivity than if you connect via wireless.
How to Fix Routing code issues on Lennar Home users via Web GUI.
How to Fix Routing code issues on Lennar Home users via CLI
Technical Support Engineer | L2 TAC Wired | Lennar Home Community