G-drive as Time Machine - get "disk not ejected properly" upon waking up

I have a G-Drive mini Gen4 500GB drive for use as a time machine backup drive on a MacBook Pro (Retina, 13 inch, early 2015) running Mojave OS 10.14.6. The connection is via a FW800 cable to a FW-thunderbolt adaptor (Apple). The laptop energysaver settings (when plugged into external power) are set for Power Nap enabled and put HD to sleep when possible. Most of the time (but not always), I get multiple “disk not ejected properly” dialog boxes on the screen when I wake the computer up.

There seem to be several “solutions” to this problem proposed on this forum (and elsewhere), but its not clear if any are the ‘correct’ solution. These are:

  1. provide external 12 VDC power to the G-drive. This drive was sold without the power supply, as it is supposed to be bus-powered. This same drive was used as the time-machine backup for the iMac that preceded the current laptop without having any of the “disk not ejected properly” issues. If having an external power supply is the correct fix, what is the part number for it?
  2. replace the FW800 cable - either with a new cable or use the USB 2.0 connection. Again, in the previous incarnation, the present FW800 cable was used to connect to the iMac.
  3. reset the SMC on the laptop. Haven’t tried that yet, but this seems to have mixed success (if any), based on reports from other forum contributors
  4. disable the ‘HD sleep when possible’ option to keep the HD running. This isn’t a very preferable option - just in terms of having the HD run all the time, even though the computer may be used less than an hour per day, on average.
  5. disable the Power Nap feature. As I understand it, Power Nap allows the computer to perform time machine backups while sleeping and perform other tasks, like check for new email, etc. This is probably an acceptable option (so functions like doing a time machine backup would only occur when the computer is awake…). Again, in the previous service with the iMac, I’m fairly certain that the Power Nap feature was enabled (I can’t check this, as the iMac has gone off to computer heaven…).

Any insights on these as ‘solutions’ (or something else I’ve missed)? I will note that as far as I can tell, the G-drive is still properly connected to the laptop (despite the “disk not ejected properly” dialong box(es)), as the time machine menu shows that backups have occurred (I haven’t checked this by going into the G-drive and looking for the latest files).