I will be rebooting our host servers tonight (physical machine) which will interrupt all of the guess servers (rebooting many of them) after midnight tonight.  This may take several hours during which you will experience interruption of services up to 1/2 hour.

     This is necessary to boot current kernels that have fixed various bugs and security issues.  Unfortunately the systemd scripts for Ubuntu are still someone buggy so sometimes it takes 3-4 attempts for a boot to succeed.