Very slow access to files and directories from Win10

I have a MBLD since 2014 in RAID1. No problems for years, now I’m experiencing a very slow access for any operation. Deleting files or directories takes tenths of minutes, anche even simply a list of a directory content does need several minutes. I tried to stop the DLNS service that I saw eating about 95% of CPU time, but nothings seems changed. The Apache server was stuk too (not answering the browser).
I restarted the system but I only get the NAS working fine for a while, let say one hour or two, then again slow access as before and the browser seems stuked again.
Notice that my laptop and the NAS are cable connected to the same Router (with Gigabit Ethernet speed), and a speed check of the connection to internet from the laptop overcome 650Mbps, so I can not imagine any network problem.
I can not figure out what’s appenging, has someome any hint?

Hi,

You may refer to the following link: https://support-en.wd.com/app/answers/detail/a_id/19820