@Clacross
General troubleshooting would be to try using a different HDMI cable or try using a different HDMI port and see if issue is resolved.
The reboot kind of indicates that it is losing the audio communication (which again, could be HDMI cable or HDMI port related). Need to eliminate those two things first as culprit.
The above is assuming you are directly connecting your Ultra 4660 directly to your TV via an HDMI and not any additional external HDMI switches or components.
@LoveDove90
The Power and Volume Button are strictly for TV control and have no affect on the Roku device, per se. I would verify that you have fresh batteries and then attempt to re-pair them to your TVs. (How to set up your Roku® voice remote ) found at https://support.roku.com/article/360011621473.
For what its worth, using the headphone jack on the remotes drains the batteries pretty quickly. Some have found unreasonably so. Additionally, it may not fully disconnect and cause issues like you experienced. I have not experienced those issues with my remote but some have. If you are a fan of the Private Listening, I think it is better to use the official Roku Remote App found in the Play/Apple Stores that you can install on mobile device. You can then connect your headphones into your mobile device or use bluetooth/wireless earbuds. Kind of a better setup since you can be charging your phone while listening to the Roku.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102
