This is required for Linux to accept the RIO
with this patch:
2001:db8:8000::/33 via fe80::d0e7:ffff:fe46:6b52 dev tap0 proto ra metric 1024 expires 86338sec pref medium
2001:db8::/32 dev tap0 proto kernel metric 256 pref medium
before:
2001:db8::/32 dev tap0 proto kernel metric 256 pref medium