Hi @Mike75043.

Welcome to the Sonos community and thanks for bringing this to our attention and thanks for doing the extra mile of starting with some basic troubleshooting steps. I would like to provide some recommendations to help you out.

I would suggest calling our technical support team for more in-depth troubleshooting steps, It is best that you be familiar with the following information so we can check our articles if we have a known issue with your network hardware since stereo pairs worked but not adding the stereo paired Sonos device as surround. There could be other causes that trigger this issue and needs further and more in-depth troubleshooting steps and investigation. There may be a setting in the router that prohibits satellite/surrounds/broadcast from communicating.

1. Router make and model.
2. Modem make and model.
3. Wifi booster or extender make and model.
4. Mesh system make and model.
5. Secondary or tertiary router make and model.
6. Other devices wired to the router.
7. Network switch or hub make and model.
8. Other devices wirelessly connected to the router.

Please let us know if you still have further questions or concerns. Here in the community, everybody can help you out.

Thanks,

Problem was resolved after calling Support. I reinstalled after moving the Sonos Ones closer to the Sonos Arc. Install was successful and then moved the Sonos Ones back to the original location.