Is Doomwiki offline?

Because I am unable to access it, it doesn't display anything for a long time, then causes a server error.

Any reasons?

It gives an Error 503 code. So you can learn what it means here:

http://www.checkupdown.com/status/E503.html

In short, it's either overloaded with queries or undergoing maintenance.

1 hour ago, Gez said:

In short, it's either overloaded with queries or undergoing maintenance.

I don't think it would ever get overloaded with queries. But maintenance may be the reason.

The server went unresponsive again as it's had a tendency to do off and on for a while now. It WAS getting less frequent and now it's back to about once or twice a week again. We've tried everything there is to try at this point, short of ditching apache and going with nginx.

10 hours ago, Quasar said:

The server went unresponsive again as it's had a tendency to do off and on for a while now. It WAS getting less frequent and now it's back to about once or twice a week again. We've tried everything there is to try at this point, short of ditching apache and going with nginx.

We could experiment with nginx in parallel to apache, on a high-port (:8443) and see how that does

But it works fine for me.

You're about a week too late.