VpnService.Builder IPv6 error null object

  builder.setSession("MyVPNService");
                    builder.addAddress(deviceIp, 24);
                   builder.addDnsServer(dnsIp)
                            .addDnsServer(dns2Ip)
                           .allowFamily(OsConstants.AF_INET);
                    builder.addDnsServer(ssd)
                            .allowFamily(OsConstants.AF_INET6)
                            .establish();

Im building the interface like this. ssd is "2400:cb00:f00d:dead:beef:1111:2222:3333" When code passes this line it throws an exception. (it works perfectly fine if i commend the ipv6addDnsServer line)

FileInputStream in = new FileInputStream(mInterface.getFileDescriptor());

*java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.FileDescriptor android.os.ParcelFileDescriptor.getFileDescriptor()' on a null object reference
       

Oh i see, builder didnt assign to mInterface so thats why its null...