Hyper-V Manager - How do I Connect to Hyper-V Server using different credentials

Add the target account credentials to the Windows Credential Manager from the command line and try reconnecting:

cmdkey /add:TARGET /user:TARGET\USER /pass

Where TARGET is the remote Hyper-V host name and USER is the username added as an Administrator to the Hyper-V server.

As an aside, after having struggled with this configuration myself, I highly recommend running HVRemote on the client and server to aide in troubleshooting potential issues.

Hold Shift while you right-click "Hyper-V Manager", select "Run as different user", and enter credentials that have rights to manage Hyper-V.

Runas would also work if you use this syntax:

runas /user:domain\username /netonly "mmc virtmgmt.msc"

You can launch mmc with runas and then select the snap in e.g.

runas /user:AlternativeUsername mmc

It's worth reading this complete guide which will get you a nice shortcut too:

Running the Hyper-V Management Tools with Alternate Credentials

If you want to connect to a Hyper-V Server that is NOT part of a DOMAIN, you can use this trick:

runas /user:NAME_OF_HYPERV_SERVER.\Administrator /netonly "mmc virtmgmt.msc"

IMPORTANT NOTE: Take notice of the period AFTER the server name.

So, if you are on a Windows 10 Machine, and do NOT want to connect to the hyper-v installed on your machine, but to another hyper-v server on your local network, and it is NOT part of a domain, you can use this. If you hyper-v server is named crunchy, then this would be the line to use:

runas /user:crunchy.\Administrator /netonly "mmc virtmgmt.msc"

Of course, this also assumes your Administrator account is called Administrator.

Enjoy!