is it getting dhcp from your router? does the address lease time perhaps match up to the time the drive is available? Maybe try reserved dhcp or static IP to troubleshoot.
Also, if the drive is in power saving mode, I don’t know if your devices will see it. I know on my LG tv, if I look for media I think it wakes the drive up, and it takes a minute to find all the thumbnails. Maybe your devices or router aren’t waking it up.
Encheck the power saving mode on the MBL for a few days and see if that helps, just to narrow it down.
