Blaming a day of multiple power outages that resulted in the OPT not working…leading down set of rabbit holes, each worse than the last. IP eventual blocked (dreading any ‘reset’ steps.) The video titled ”Locked out of Synology? - How to Soft Reset Synology NAS” referenced using the cell phone for a fresh IP. That mention triggered the thought of TailScale (which I think you also published video’s on) ~ and Tailscale worked.
Back in > deleted OTP > reset clocks on al ldevices > added new OTP and back to normal.
Thank you.