I have the same problem on my server.
kern.version=OpenBSD 6.2 (GENERIC.MP) #6: Wed Feb 28 21:13:02 CET 2018
r...@syspatch-62-amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP
Everything works fine except until the end.
acme-client: https://acme-v01.api.letsencrypt.org/acme/new-
It seems Let's Encrypt have changed the address of the full chain
certificate, so it's now a 301 redirect that acme-client can't follow:
$ doas acme-client -vv walcyrge.org
[...]
acme-client: http://cert.int-x3.letsencrypt.org/: full chain
acme-client: cert.int-x3.l
