Just a heads up, wiki's throwing this error again. Been trying to use the wiki since around 5:45 AM (2/16/19). 504 is almost constant. I've been able to get in twice between 5:45 and 7:30 AM, but it remains accessible for only a few minutes at a time. Once I am inside the wiki, if it goes down while I have a page loaded and I click a link to a new page, I get a "502 Bad Gateway" error.
So, happy Saturday TonyV, or Blondeshell, or whoever has to deal with this! :-) (And, can't be said enough, thanks again for all your time and effort.)
Note: 7:35AM now, wiki's back up and seems stable for the moment.