I find it interesting that the site won't work for me usually in the evenings, and sometimes mornings (UCT+2). Yet, it only rarely occurs that it won't work during the day.
Also, while this happens, every other site I check on a regular basis works fine.
I'm suspect that it's an issue with a local, or at least close-by routing node that the forum/IRC/site use. I suspect this because we have people from different continents with the issue.
EDIT: Huh, something weird happened just now, something I might need to investigate further, in time.
Since the forum wasn't working, I tried restarting the router a couple of times, until something changed in the DNS. Happened that after the secondary DNS managed to change by one digit and a few more seconds, it works. I also noticed how the router had reconnected whilst I wasn't using the internet, which led me to try a few restarts.
IRC not working, no matter what, though.