Re: sysupgrade can't reach nycdn.netbsd.org

[Greg Troxel <gdt%lexort.com@localhost>]

[I agree with everything mouse@ said.]
The next thing to check is if you have an IPv6 default route;

   netstat -nr -f inet6

and also to restart dhcpcd and look at the logs.

On an arm device (to stay on topic :-) on my local network, there is a
v6 address starting with 2001:  and a small last octet (assigned
manally) and an address with the same prefix and a SLAAC
(https://datatracker.ietf.org/doc/html/rfc4862) address where the bottom
64 are random or derived from the MAC addr.   I also have a fe80 link
local address.

I am guessing you have a v6 default route, do not have a global address,
but have a site-local address -- which can be routed among systems on
your site, if you had a lot of "links" aka Ethernet segments.

I would examine the configuration of your router (that does dhcp and v6
router adertisements) and also other computers.  Arguably it should not
be configured to hand out site-local addresses, unless you understand
the issues and want that.  IMHO wanting site-local addresses is unusual,
and for experts.