RBR40 changed internet service provider and now can't access secure pages

We have an RBR40 wireless mesh system with two satelites. Yesterday we switched out internet from Spectrum to ATT.  We made no changes to the router, simply switched the ethernet cable from the Spectrum modem to the ATT modem.  Everything seemed to work and I was able to work normally using Zoom and all other tools.  However the installer left before fully testing everying, and when I tried to use Prime Video on my Samsung SmartTV (10 feet from the router) it would not connect, nor would any other streaming service.  Then I noticed on my computer that certain secure pages gave me a 404 page not found error and said it was due to security. I spent 2.5 hours online with ATT internet support and they connected to both the modem and the router and could not solve it and told me to contact Netgear support.  Since I have had this product for almost 3 years, I will have to pay for help so reaching out here to see if anyone can help me with the security settings in my router that might be causing this.  Using the ATT wifi works as normal. But this does not give me a good signal downstairs which is why I bought the Orbi in the first place.