I cannot reach my Owncloud website when I try to access it from my desktop pc, the site appears down with any browser or application on this one. However, other devices connecting to the internet through the same gateway, as well as anywhere else on the internet, can reach it.
This pc used to be the actual server that my Owncloud resided on. I had my OpenWRT router spoof the site's IP address to the server's internal one, i.e. all the devices that connected to my router and called this URL where redirected to the OC server's internal IP instead of taking the long route over the internet.
Now, my OC is hosted remotely, site and I use this pc just as a regular workstation. I wasn't able to remove the hostname from the router's settings (some stupid bug), so I thought that was the reason why my pc, sitting behind it, still kept getting rerouted to itself when looking for the OC site. I tried taking the router out, the pc now going directly to ISP's the modem, so that hostname should be out of the game.
However, the problem remains, so I have reason to believe there is something on my very system misdirecting the DNS.
Any ideas where I might best start looking?

Try a traceroute to the site from the problem machine and from a machine that works. Comparing the outputs should give you a hint as to where the failure is occurring.

This is exactly it: For some reason it believes that URL is on my localhost.
Doing this on another machine gives the same output except with my OC site's correct IP...

...And, in case that wasn't clear, I have no idea why that is, and how to fix it (problem not solved).

Do you have something like this in the /etc/hosts file on that machine?

If so, remove it (or comment it out).

Yes! Done! Problem solved, thank you very much! :-)