You're going to need to provide a lot more information than that to allow anyone to give you meaningful advice/assistance.
What model of arris?
Is it just a modem or is it a router? Unusual for ISP to provide just a modem (here in the UK anyway).
Are you using the Orbi as the router or in Access Point mode? I assume router as you refer to the arris as a modem. Is this the same as with your previous ISP?
Have you accessed the modem's GUI and looked at the settings?
What troubleshoting have you tried?
