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Setting your Arris SBG6700 gateway to bridging mode disables the internal router, Then in order to connect multiple devices you must have a separate active router fed from the gateway's LAN 1 port.
You must put the 6700 back into normal mode AND do a full reset to factory defaults.
Ok, the only way it stays on the normal setting and not bridged is when the coax cable isn't plugged in but as soon as it is it reverts back to bridge.
Thanks again for the responses.
You may need to call in to Spectrum and have them adjust the provisioning of the gateway if they have it set on their end for bridge mode.