fe80:: is a IPv6 link-local address, so that's not a public IP. Those can be used within a network, but not across routers.
So if the fe80::... IP is the one you are using i'm positive it's not the right one to use.
Ah, also this makes little sense:
ping6 < my_ip> 1433
because ping does not know about ports. Try using
$ telnet -6 <my_ip> 1433
instead, if you want to check the tcp connection.
As far as the error message is concerned
connect: Network is unreachable
you will also get this message if your client host doesn't have IPv6 connectivity.
Try this on your client
$ telnet -6 google.com 80
and see if you get a connection or if you get Network unreachable.