500 Can't connect to math.utm.edu:80 (Connection timed out) at /opt/webwork/webwork2/lib/WebworkClient.pm line 293.
seems to suggest a similar problem to the discussion about problems in Docker in http://webwork.maa.org/moodle/mod/forum/discuss.php?d=4173 so that thread may be related.
In that case, the "server" (the Docker container) did not know how to route traffic to itself, which caused the "500 Can't connect to ..." error.
Adding an extra record to /etc/hosts to make sure the machine can resolve its own FQDN (fully qualified domain name) without use of DNS may help.
(Edited by Michael Gage - original submission Wednesday, 21 November 2018, 12:48 PM)