Substitute server error authenticating

[Bone Baboon]

I am trying to set up a substitute server.

The substitute server starts fine with this command `guix publish
--user=username --compression=gzip:9 --compression=zstd:9
--compression=lzip:9 --cache=/home/username/publish-cache/
--cache-bypass-threshold=0 --public-key=/etc/guix/signing-key.pub
--private-key=/etc/guix/signing-key.sec`.

On another computer I have run `guix archive --authorize <
<substitute-server-public-key>`. When I try to run `guix pull
--url=<substitute-server-address>:<port>` I get this error "guix pull:
error: Git error: error authenticating: no auth sock variable".