I have been trying to use smart bulbs in my dual head motion sensor fixture. I get them paired up with my wifi but they go off line rather quickly. I realized that I was pairing them in test mode on new fixture. Is the power cut to the fixture when I change it to dusk to dawn? Could yhat be why my connection keeps getting interrupted? The switch operating the fixture is always on, but does the setting change the power to it?
Your control systems are incompatible
This is one we see all the time. People try to dim their remote controlled fan. Or a timer with a motion sensor. Or get their modern era smart switch to play nice with a series dimmer in 3-way mode.
Bottom line: one thing must control the light. One thing. It must be the master of the light. And then, other things which are compatible may interact with it, if they are compatible. So for instance a smart dimmer that supports compatible remotes, and then, a compatible remote.
And if you need to glue a bunch of crazy contradictory control methods together, then you need to use smart-home/Internet-of-things technology. Like a Wemo or Alexa hub. Then, you install each control method so it talks to the hub, and write software code to define what each control does in each existing condition.
In your case, you need to tear apart that motion sensor kit (motion sensor + lamp stalk combo) and replace the motion sensor with a motion sensor that talks to your smart home platform. Then, you define in software "if motion sensor detects and not daylight and light not on, turn on".
To me this is obvious - but when your security light fixture turns the lights off, that's exactly what it does ... it shuts off the power to the bulbs.
So - yes, your smart bulbs are getting their power shut off and they certainly won't remain connected to your WiFi network when they don't have power.
The fixture doesn't know or care that you have smart bulbs installed, and it's simply doing what it's designed to do.
How else would it turn the lights off if it didn't shut off power to them?