I have replaced my Windows NUC with the Linux based SonicTransporter. Not really used it other than minimal testing, in the process of copying content over.
But similarly, it originally saw the SonicOrbiter and after a day or so lost it. The Orbiter has no network configuration changes and is plugged into an Eero, must be DHCP. But I don’t think it is a lease expiration issue in the Orbiter, it has worked with the Eero for weeks.
The SonicTransporter also doesn’t see the 818. I previously had it direct-wired to the NUC with static IP, now use a switch plugged into an Eero. Will try going back to DHCP.
Did I mention that networking sucks? The failure mode is crickets.