I was having trouble with MyCloud taking a long time to appear in File Explorer, as well a mysteriously failing to respond after being in use for a while.
I resolved this issue by a) making my router the Samba Master Browser (requires compatible firmware), and b) editing the Samba configuration file on the MyCloud to remove it from Master Browser contention.
local master = no
domain master = no
preferred master = no
os level = 0