The important stuff is here:
Nov 05 15:00:39 ourschool.edu <http://ourschool.edu>
/usr/bin/x2gostartagent[1221]: started nxagent: NX_TEMP=/tmp x2goagent
X2GO_NXAGENT_OPTIONS (' -extension XFIXES -nolisten tcp') NOLISTOPT ('-nolisten
tcp') X2GODPIOPTION_ ('-dpi 72') XDMCPPOPT ('') -SESSION_TYPE ('-D') NOEXITPARAM
('') -auth "XAUTHORITY" ('"/home/localguy/.Xauthority"') agent_geometry
('-geometry 800x600') -name "SESSION_WINDOW_TITLE"
('"X2GO-localguy-161-1509912037_stDXFCE_dp32"') "NX_AGENT" ('":161"')
2>"SESSION_LOG"
('"/tmp/.x2go-localguy/C-localguy-161-1509912037_stDXFCE_dp32/session.log"') &
So, at least for the local user, it's really using the local Xauthority file,
which, as we've seen in earlier mails, is part of the /home partition that is
locally mounted via LVM. We probably can assume, that this file is accessible
all the time.
This can't be a firewall issue, since nxagent is trying to connect to its
internal display in this case, which uses the local transport protocol (on
Linux, that should always be a UNIX transport).
This, still, leaves only local authentication and I can't really figure out
what's wrong. The cookie should have been added correctly to the authorization
file and at least one of the entries we add should match.