Follow ISO15118-2-2014,7.10.1.2 Supported ports

[Baymax-Rob]

The table 15-Supported UDP ports for SDP, the SDP client source port at the EVCC in the range of Dynamic ports(49152 - 65535).

I think it is necessary to add a line of code "sock.bind(("", randint(49152, 65535)))" in "evcc/transport/udp_clinet.py":

@staticmethod
     def _create_socket(iface: str) -> socket.socket:
         """
         This method creates an IPv6 socket configured to send multicast datagrams
         """
         # Initialise the socket for IPv6 datagrams
         # Address family (determines network layer protocol, here IPv6)
         # Socket type (datagram, determines transport layer protocol UDP)
         sock = socket.socket(family=socket.AF_INET6, type=socket.SOCK_DGRAM)

         # Allows address to be reused
         sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

         # The socket needs to be configured with a time-to-live value (TTL)
         # for messages to 1 so they do not go past the local network segment.
         ttl = struct.pack("@i", 1)
         sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_MULTICAST_HOPS, ttl)

         # Restrict multicast operation to the given interface
         # The IP_MULTICAST_IF or IPV6_MULTICAST_IF settings tell the socket
         # which interface it shall send its multicast packets. It can be seen
         # as the dual of bind(), in the server side, since bind() which controls
         # interface(s) the socket receives multicast packets from.
         interface_index = socket.if_nametoindex(iface)
         sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_MULTICAST_IF, interface_index)
         #Add
         sock.bind(("", randint(49152, 65535)))