Odd problem: Can't log in to some characters while at work

So, this just started happening yesterday. While at work, I tend to log in and do some background tasks like checking auctions and/or fishing. However, I now cannot login to on my Level 1 bank alt character. Whenever I try, the loading screen gets stuck at 90% and then it takes me back the character screen saying “world server is down.” My other characters work fine.

I initially thought it was addons or something causing this, so I did a clean reinstall, but nothing changed. Then when I went home after work, everything was working as normal. I could login to all characters.

Why can I not login to this specific character while I’m at work only?