I just wanted to share a solution to a challenging, poorly documented issue (as far as my research found).
3 parts to allow managing a remote system with Computer Management\Storage\Disk Management:
- On both systems (one you are trying to manage, and the one you are on), enable firewall rule group Remote Volume Access (I turned on rules only for Domain profile)
- On both systems (again, one you are using and your target system) need to have Virtual Disk Service started (or at least set to Automatic Startup, I believe default is Manual)
- On the system YOU (the manager) are on, you probably need to ensure that somehow, someway, the TARGET COMPUTER ACCOUNT (it's DOMAIN computer account) has, on YOUR SYSTEM, the User Logon Right Access this computer from the network. I achieved this by adding the target system to my local system's Remote Desktop Users group, because that and Administrators are the only two groups granted this URA by the "MSFT Windows 10 2020 - Computer" baseline GPO.
BOOM! Totally works to a remote system now. In my case, both systems are Windows 10 2004.
You probably wouldn't want to add "Domain Computers" permanently to all your IT Techs' PCs as Remote Desktop Users, but you could add them temporarily just when you need to remote disk manage something for a ticket, then remove it. Cheers!
@ajm-bthanks for sharing, never guessed the reverse firewall rule must be enabled too 
By enabling the following 3 firewall rules on the remote server, the Disk Management service can be started from remote and step 2 is not needed to start the service manually;
- RVM-VDS-In-TCP Remote Volume Management - Virtual Disk Service (RPC)
- RVM-VDSLDR-In-TCP Remote Volume Management - Virtual Disk Service Loader (RPC)
- RVM-RPCSS-In-TCP Remote Volume Management (RPC-EPMAP)