I have a Doorbell 3 Plus and had similar issues when I first installed the solar panel. What I found was;
The device will show ‘Not Connected’ until the battery drops below 90% and will then show as connected and be able to charge the device. See here Charging the Battery for Your Ring Video Doorbell 3 – Ring Help ’ Note: To maximize battery life, your Ring Video Doorbell 3 does not begin its automated recharging cycle until the battery reaches about 90%’
My solar panels (for doorbell and spotlight cams) will show as not connected if the last device health check was done at night. When it’s sunny you can perform a live view of the device which will also perform a device health check. Wait a few minutes and then re-check the solar panel status.
More info here which may help: High failure rate with Ring 3 Solar Panel? - Products / Video Doorbells - Ring Community