Arkane, someone mentioned that they had the same problem and it was because of their proxy settings; the trading post is a web page so your internet connection configuration affects it.
So you might try going to Internet explorer → Connections → LAN settings and disable everything there. (Or enable the proxy if you are playing from somewhere that needs it to access web pages.)
So trading post was down last night EU time. And it’s down now. I don’t know if it was up at any point in between. (Underworld server)
No mention of trading post problems in the latest game status update. This is getting unacceptable.
Edit: It’s up now, I suppose it was down for the update below.
(edited by Myto.3826)
Not affiliated with ArenaNet or NCSOFT. No support is provided.
All assets, page layout, visual style belong to ArenaNet and are used solely to replicate the original design and preserve the original look and feel.
Contact /u/e-scrape-artist on reddit if you encounter a bug.