OS upgrade making me bonkers

I recently had to upgrade my OS to High Sierra…I have an iMac from 2011, so I cannot go to Mojave. I encountered problems the last time I did this, and this is no different. This time, my external hard drives, I have four of them, will turn off and show up as “ejected.” I don’t know if this is an OS issue or if I need an upgrade to software for the WD externals, or perhaps there is a setting I need to change. I have had these externals in place for several years with no problems.

Here’s what works…sometimes. I have to either restart my mac, or completely shut it off, reboot it, and sometimes all of them appear in the finder. Other times one or more will be missing and I have to go through the process again. It is very annoying. I am a photographer and all of my images are stored and backed up on these externals, so when I am trying to access a photo, I will sometimes get a message that it is a corrupted file, or that it cannot be read, and that’s when I discover that the external is not connected.

Any advice, please make it simple. I am not a computer geek. Thanks.

You can follow the steps to troubleshoot given in the link below.

If still the issue persists, you should contact WD Support from the link given below.