ipv6 can not work for direct type interface

Hi there, I have a question regarding direct type interfaces. Would someone be able to take a look at it? When I start 2 VMs on the same host with interface "direct type + bridge mode", just as below: <interface type="direct"> <mac address="52:54:00:9e:7b:51"/> <source dev="eno1" mode="bridge"/> <model type="virtio"/> </interface> The 2 VMs can connect to each other via ipv4, but can not connect to each other via ipv6. Maybe it's related to some kernel parameters, but I don't know how to debug. Is there anyone who can help me? Thank you! BR, Yalan