cpo@LR1.wue3# show interfaces vxlan
 vxlan vxlan0 {
+    group 254.0.0.1
     source-address 172.18.254.201
+    source-interface dum0
     vni 10
 }

Traceback (most recent call last):
  File "/usr/libexec/vyos/conf_mode/interfaces-vxlan.py", line 114, in <module>
    apply(c)
  File "/usr/libexec/vyos/conf_mode/interfaces-vxlan.py", line 103, in apply
    v = VXLANIf(**vxlan)
  File "/usr/lib/python3/dist-packages/vyos/ifconfig/interface.py", line 317, in __init__
    self._create()
  File "/usr/lib/python3/dist-packages/vyos/ifconfig/vxlan.py", line 79, in _create
    self._cmd(cmd.format(**self.config))
  File "/usr/lib/python3/dist-packages/vyos/ifconfig/control.py", line 52, in _cmd
    return cmd(command, self.debug)
  File "/usr/lib/python3/dist-packages/vyos/util.py", line 161, in cmd
    raise OSError(code, feedback)
OSError: [Errno 255] failed to run command: ip link add vxlan0 type vxlan id 10 dstport 8472 local 172.18.254.201 dev dum0 group 254.0.0.1 tos inherit ttl 16
returned:
exit code: 255

noteworthy:
cmd 'ip link add vxlan0 type vxlan id 10 dstport 8472 local 172.18.254.201 dev dum0 group 254.0.0.1 tos inherit ttl 16'
returned (out):

returned (err):
Error: argument "254.0.0.1" is wrong: invalid group address

[[interfaces vxlan vxlan0]] failed