Problem: You need to connect a Hyper-V Server host to Veeam B&R Console to create a VM backup job but you cannot connect despite remote host FQDN/IP Address and credential are the current ones.

Connect your Hyper-V server via PowerShell remote session, RDP or the way you choose. If not PowerShell remote sesion, you need to run PowerShell as admin then enter the following commands,

New-NetFirewallRule -DisplayName "Veeam Ports" -Direction inbound -Profile Any -Action Allow -LocalPort 135,137,139,445 -Protocol TCP
New-NetFirewallRule -DisplayName "Veeam Ports" -Direction inbound -Profile Any -Action Allow -LocalPort 135,137,139,445 -Protocol UDP

These ports will allow Veeam Backup & Replication Console to deploy required components to Hyper-V Server.

You can test if the ports are open with the following command if necessary,

$rule = "Veeam Ports"
Get-NetFirewallRule -DisplayName $rule | ft -Property Name, DisplayName, @{Name='Protocol';Expression={($PSItem | Get-NetFirewallPortFilter).Protocol}}, @{Name='LocalPort';Expression={($PSItem | Get-NetFirewallPortFilter).LocalPort}}, @{Name='RemotePort';Expression={($PSItem | Get-NetFirewallPortFilter).RemotePort}}, @{Name='RemoteAddress';Expression={($PSItem | Get-NetFirewallAddressFilter).RemoteAddress}}, Enabled, Profile, Direction, Action