I upgraded the PSTK to 188.8.131.521 and tested it against an ONTAP 9.8 cluster. PowerShell version: 5.1.19041.1320 on Windows 10. No issues connecting to the cluster via FQDN or IP Address using:
Connect-NcController -Name <cluster> -HTTPS -Credential (Get-Credential -Credential <user>)
Do you get the same error connecting to the cluster from all systems?
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