SBG6950AC2 Bridge Mode?

I’m replacing an old Arris Modem, specifically SB6190 with a SBG6950AC2, and the old modem was connected to a router made by Araknis. When I set up the new Modem, I was able to get wireless internet through two new SSID’s coming from the new modem. However, our old SSID is still available to connect to without internet access. Most importantly, I have multiple range extenders, and access points connected to the old router via Ethernet that are not giving out internet access anymore since the modem has been replaced. I attempted to switch the new modem into Bridge (NAT Mode) however that made it impossible to connect to the new SSIDs and the old SSID. I am trying to get the internet coming from the new modem to be broadcasted on the access points/extenders throughout my house. There are also multiple hardwired (ethernet) connected devices throughout my home that are connected to the router and haven’t had internet access since the modem replacement.