Thanks for your advice. Do you have any idea why the server is unable to ping its default gateway? From the gateway I can see the server's mac address and I can ping to the server, but the server can't ping. I have checked the server's NIC (restarted), there is no firewall between them, and vlan 10 is allowed on the peer-link connection.
Correct method is to use HSRP on both with SVI on both even if it's an orphan port. It will work though if you only do it on one but then don't configure it on the other, or configure that vlan on the other, and you have to exclude that SVI from being taken down if the VPC link fails.
Realistically I would not plug anything into a VPC unless it was in a port-channel, that is really the correct way of doing it , even a server. Anything else you are asking for issues or complicated configs to make it work.