user sharing - won't shutdown

for a few years I've been running a cMP3,1 (10.13.6 High Sierra) as the drive server for media.

The apps, Emby and JellyFin are running off an '18 Intel mini (12.7.6 Monterey).

They connect via an unmanaged LAN switch.

The drives in the cMP mount as "log-in" items from the mini.

Never an issue.

I have a scheduled shut down for both Macs at 2a and restart at 7a ... just coz.

Suddenly, the cMP won't shut down coz "A user is connected and sharing ..."

Tried a safe start to perhaps clear an issue. pRAM zap. SMC. Onyx.

Nada. No new software, nothing is different.

Other than the cMP lost 2 sticks of ram. So I have 4 on A and 2 on B. All matched properly other than the "imbalance".

I'm the only user and behind a VPN.

Any ideas?