Nexux 9k primary Vlan lost when Router down

[sufyan.a1]

i have two nexus 9504 connected via vPC link, and  working as active passive as show in diagram. and i config the HSRP on both nexus, where NX1 has VLAN 30 with IP 10.20.30.2 (Acive)and the NX2 has the IP 10.20.30.3(Standby). and the Virtual IP is 10.20.30.1,  when the router goes down in can't ping the active IP(10.20.30.1,10.20.30.2), any one has idea why this happen.

regards,

[nazimkha]

Assuming the router going down you are referring here is the Nexus switch.

If you are failing the vPC primary nexus switch, what is the state of vPC on the secondary switch.
vPC loop avoidance kicks in if the it goes down in certain sequence.

Output of the following will help before and after the failover on both the Nexus switches
show vpc
show interface vlan 30
show hsrp interface vlan 30
show hsrp brief