There’s 2 lights on the front of the sbg8300. They both don’t come on? 

Did you put it in bridge mode? 

Have you tried a factory reset? 

General FAQs: SBG8300: LED Light Status (salesforce-sites.com)

Only the online light comes on. 

How do you put it bridge mode?

How do you factor reset?

Don’t put it in bridge/modem only mode. that does disable the wifi. 

General FAQs: SBG8300: Factory Reset (salesforce-sites.com)

Well after performing the Factory Reset could you let us know the LED light status of the sbg8300 that's the online and Wi-Fi?

Could you also let us know when you purchased the modem? The name of your ISP(Internet Service Provider)

Is this a First-time activation if so have you activated it? by providing HFC MAC ID?