For everyone who would stuck with that, I found a solution, thanks to @murat1981 .
Short answer would be - re-plug the LAN cable on device. It would re-initialize device inner state, as I understood, and it’s back to normal speeds.
After I plugged out my My Cloud Home 8TB single bay device from switch, plugged it back again, it reinitialized network connection, and now kdd speeds is back to normal.
I’m on Win10 64-bit. Short-way-to-MyCloudHome in my network is:
PC_LAN - UTPCat5E (about 5 meters long) - D-Link-DGS-1210-28/ME - UTPCat5E (about 2 meters long) - MyCloudHome
I plugged out and plugged in the MyCloudHome cable from D-Link side.
Also, I had a look at web-interface, and had a look at switch indicator for port before re-plugging the cable. Both reported that MyCloudHome link speed is “1000M Full” (indicator was green, and port status in switch web-interface also reported as “1000M Full”).
Dear WDStaff, I had download debug logs from my MyCloudHome device after I re-plugged my device to switch and seen improvement in transfer speeds and kdd-process-improvement, could it be useful for you to investigate the issue?
Now I am waiting till it would break again…