Here are the elevated PowerShell commands to run to set the virtual directory URLs

Get-ActiveSyncVirtualDirectory -server EXCHANGE | Set-ActiveSyncVirtualDirectory -ExternalUrl ‘https://mail.DOMAIN.ca/Microsoft-Server-ActiveSync’ -InternalUrl ‘https://mail.DOMAIN.ca/Microsoft-Server-ActiveSync’
Get-AutodiscoverVirtualDirectory -server EXCHANGE | Set-AutodiscoverVirtualDirectory -ExternalUrl ‘https://mail.DOMAIN.ca/Autodiscover/Autodiscover.xml’ -InternalUrl ‘https://mail.DOMAIN.ca/Autodiscover/Autodiscover.xml’
Get-ECPVirtualDirectory -server EXCHANGE | Set-ECPVirtualDirectory -ExternalUrl ‘https://mail.DOMAIN.ca/ECP’ -InternalUrl ‘https://mail.DOMAIN.ca/ECP’
Get-OabVirtualDirectory -server EXCHANGE | Set-OabVirtualDirectory -ExternalUrl ‘https://mail.DOMAIN.ca/OAB’ -InternalUrl ‘https://mail.DOMAIN.ca/OAB’
Get-WebServicesVirtualDirectory -server EXCHANGE | Set-WebServicesVirtualDirectory -ExternalUrl ‘https://mail.DOMAIN.ca/EWS/Exchange.asmx’ -InternalUrl ‘https://mail.DOMAIN.ca/EWS/Exchange.asmx’
The elevated PowerShell commands to verify the settings:

Get-ActiveSyncVirtualDirectory | fl internalurl,externalurl
Get-AutoDiscoverVirtualDirectory | fl internalurl,externalurl
Get-ECPVirtualDirectory | fl internalurl,externalurl
Get-OabVirtualDirectory | fl internalurl,externalurl
Get-WebServicesVirtualDirectory | fl internalurl,externalurl
Please note that we run a split DNS setup to have the external URL map to an internal IP address while folks are in the office (as per SBS STD).