Question Hard drive speeds sluggish

[uk152019]

I have a file server with documents opening/closing very slowly when accessed via the network share.
I am not 100% familiar with I/O speeds-can someone tell me if these are acceptable?
About 10 users accessing the share.
The share is on a D: partition, with C: on the same disk (not good practice, I know).

CrystalDiskMark screenshot here: https://a.uguu.se/qcCoG3RikIdo.png

Thank you!

 

[Ralston18]

More information needed:

make and model drive, capacity, host system hardware specs?

Any encryption, any indexing?

Any known changes prior to the sluggishness?

How full is the drive: total drive and respective partitions?

Windows 10: observe what is happening to the drive(s) using Task Manager and Resource Monitor.

Is the drive backed up (at least twice with both backups verified as readable and recoverable)?

Have you run any of the drive manufacturer's diagnostics on the drive?

 

[popatim]

Server config plz, esp the disk(s)/array.