By browsing your “router” which you enter on Safari as 192.168.0.1 <== this number can vary with different households, you can find the ip that is assigned to your cloud. This is the same ip that you use for your dashboard on Safari, like 192.168.0.15 which brings up your Cloud Dashboard.
Once you get the ip, map by click on “GO” in your Finder Menu, then select “Connect to Server”
Type in your server Address, or click on Browse to see what is on your local network. At my house I am using a new AC WiFi Router on top of my existing internet router so what happens is that I cannot see my Clouds because they are on another network. I think this is the trouble that a lot of users get into. If you cannot see your Cloud using Browse, you can access your Cloud using an IP and you have to determine that IP on your own; either by viewing your router status or logging page, or by guessing and trying incrementally ip numbers on the safari page
here are some examples of mine
smb://192.168.0.16 <== this is a cloud that is set to DHCP and has gotten the ip from the old router
smb://WDMyCloud/Cloudy <== same cloud that was set to DHCP but you have to be on the same network i.e. 192.168.0 otherwise the name of the device WDMyCloud won’t resolve itself. This name is set on your Cloud Dashboard and the default is WDMyCloud. Cloudy is the share name that you create under shares.
afp://192.168.0.16 <== connecting using afp. AFP is slower for file transfers but quicker for huge directories like photos, ebooks or music. When I say huge, I mean 10,000 entries or more. Use SMB for all or most connections.
My Mac has two different network connections. When it uses WiFi, it has an ip of 192.168.100.26 <== notice the 192.168.100. When it is on ethernet, I use a fixed IP of 192.168.0.123 <=== notice the 192.168.0
So I think I covered everything. I had never had a problem with El Capitan through its various versions. I have a Macbook 12" that sleeps and switches between ethernet and Wifi with the clouds connected between the switching. I have another mac that is permanently connected to one of the clouds for my entertainment center that sleeps for most of the time.
None of my devices disconnects from my mac… unless… my router resets… then you might see a mapped drive drop out.
Good luck…