IPv6 RA inside UnRAID VM not accepted

[Leseratte10]

I'm running an UnRAID host with 6.11.5, and a bunch of VMs (network source br0, network model virtio-net) all running Debian 11. All VMs have "net.ipv6.conf.*.accept_ra = 2" set.

 

One of the VMs is running radvd, announcing a route to the network: 

interface enp1s0 {
    AdvSendAdvert on;
    AdvDefaultLifetime 0;
    AdvDefaultPreference low;
    route 2001:db8:1234::/48 {
    };
};

 

Other devices on the network, Linux and Windows, are picking up this route just fine. "ip -6 r" on Linux, or "route -6 print" on Windows will display the route and use it. The UnRAID host itself and the other VM running on UnRAID, however, don't. 

 

Running a tcpdump or something like radvdump confirms that the route advertisements do reach the UnRAID host and the other VMs:

 

#
# radvd configuration generated by radvdump 2.18
# based on Router Advertisement from fe80::xxxx:xxff:fexx:xxxx
# received by interface enp1s0
#

interface enp1s0
{
    AdvSendAdvert on;
    # Note: {Min,Max}RtrAdvInterval cannot be obtained with radvdump
    AdvManagedFlag off;
    AdvOtherConfigFlag off;
    AdvReachableTime 0;
    AdvRetransTimer 0;
    AdvCurHopLimit 64;
    AdvDefaultLifetime 0;
    AdvHomeAgentFlag off;
    AdvDefaultPreference low;
    AdvSourceLLAddress on;

    route 2001:db8:1234::/48
    {
        AdvRoutePreference medium;
        AdvRouteLifetime 0;
    }; # End of route definition

}; # End of interface definition

 

However, the advertised route seems to not be added to the routing table. 

 

Is there some kind of setting inside UnRAID that could be blocking these? Both the UnRAID host and all the VMs correctly receive and use routes advertised by another physical machine on the same network, just RAs from the same physical machine seem to be ignored. Or could this be a configuration issue in the Linux VMs in that Linux somehow still figures out that the RA actually comes from the same physical device?

 

The link-local address the RA is from (fe80::xxxx:xxff:fexx:xxxx) is the link-local address of the VM running radvd. 

I have attached the configuration from the radvd VM extracted from the Diagnostics. 

vmconfig.txt