I've two n3500 connected and running 4 x ESX Hosts (6.5) via vPC trunk without issues - the hosts are reachable from both switches and from other networks - the vmkernel uses the mac from old network card, not the one connected to n3500 and the management vmkernel is without configured VLAN (uses the native vlan set on the vPC).
Now i want to add additional ESX Hosts (with ESX 7.01), made new vPC exactly configured like the other four existing and now i'm running in the issue that the Management vmkernel IP is only reachable from one of the two n3500, when i disable the interface on the other switch it's working fine. Funny that after adding a second vmkernel (which got directly a virtual mac and didn't take one of the physical macs from vmnic) this one was reachable from both switches. The MAC from first vmkernel with management IP was already changed to a virtual mac but still the same issue - as soon i've enable the the network interface on second vPC switch only the second vmkernel is reachable but not the first one.
The vPC status is success, so no issues shown there.
I think it's something with ARP cache (in show ip arp the IP is not shown with MAC on the second n3500) but i'm stuck somehow.
Any hints maybe? I guess it's just some small missing setting but i'm running out of ideas now.