NL-Network-01 error does not have any details, so what does it mean. Why am I getting very high numbers of these errors?

I am running a load test wherein at random interval there are bursts of these errors and they have no details mentioned.
Also, with same scenario, in different run there are other messages which says - java.nio.channels.UnresolvedAddressException in neoload

What is the reason for these 2 error messages.
Thanks