I'm trying to understand, how the UDP sock API  works, but the documentation /example are very bad / useless.
My questions are:
1: How can I create an UDP server which listen on a specific port and has an unique IPv6 addr ?? The example  isn't very helpful. I don't understand why some variables like "local"  are defined. The documentation does not help. The documentation says "Common IP-based transport layer end point." for the struct sock_udp_ep_t. But why do I need this?? I want to receive and send udp packages to other boards. Why is this so difficult to implement ??
2: How can I send an udp package with the following parameters given: - message - portnumber - dst ipv6 addr
The documentation / example does not help here either.
3: How can I get the unique Ipv6 addr from my device (samr21-xpro). I want to call "getIPv6()" and want the Ipv6 addr which this device has.
 https://doc.riot-os.org/group__net__sock__udp.html  sock_udp_ep_t local = SOCK_IPV6_EP_ANY;