Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.
The basic troubleshooting steps are :
- Firstly, please check the ARP status using ARP tables for private peering
- Depending on the hardware platform, the ARP results may vary and only display the On-premises interface.
- Then, if ARP is fine, check BGP. You can refer to this : Validate BGP and routes on the MSEE
- And check if the BGP routes are being advertised properly between OnPrem and the Circuit.
- Now, validate the VNET Gateway using Get-AzVirtualNetworkGatewayLearnedRoute
- And make sure the VNET gateway is learning the route from circuit. (the origin type will be "EBgp" )
- Additionally, you can also check if a VM in the VNET is learning the OnPrem route or not
- NIC effective Routes
- See if OnPrem address prefixes are learned or not
- NIC effective Routes
However, you confirmed there was a port down on your end.
Thanks,
Kapil
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