Took me a bit to figure this out, so posting here in case others run into this, I consider this solved.
For a service I wanted to run on NetBSD, I had to open a port to the outside world on my home internet router as "port-forwarding". But the port had issues being seen. I did some poking around and I discovered the issue was due to "/etc/hosts" and "/etc/myname".
By default "/etc/hosts" has these lines:
::1 localhost localhost.
127.0.0.1 localhost localhost.
and "/etc/myname" has a line like this:
sysname.domain.com
To correct the issue, I had to add these 2 lines to "/etc/hosts":
::1 sysname.domain.com sysname
127.0.0.1 sysname.domain.com sysname
All is working fine now. Note, strings "sysname" and "domain" and "com" you would change to your needs.