The other day we had a problem on one of our servers that caused the memory usage to skyrocket. After this event our shared Gluster drive was inaccessible by this server. While troubleshooting I received the following message:

ls: cannot access shared: Transport endpoint is not connected

After a lot of high pressure Google searches I found the following works to fix this:

fusermount -uz /path/to/mount
mount /path/to/mount

Hopefully, this will help someone else as well.