I applied package updates including security fixes to all workstations.

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k1ctr11 and 21@Mozumi hung up, I recovered them before this update.
Because NUC workstations freezes frequently, I set to periodically check whether the GUI is running properly on the NUCs (k1ctr11, 14, 15, 20, 21) same as monitor workstations. It may be able to recover problematic workstations automatically. (I'm not sure it works fine or not because I haven't identified a cause of this issue yet.) If checker script can be launched after the GUI hangs up, some kind of logs can be obtained at least.

k1ctr12@PSL is still link to 100Mbps (See also klog#36410).
Due to slow network speeds, the NFS mount timed out while the OS was booting up, so I had to mount NFS regions manually after the OS had started.