I’m encountering this same error. I have dealt with it in the past once and it fixed after re-installing the game.
Two days ago I encountered the “Connection error(s) detected Retrying…” problem and then messed with my router thinking it was the problem. It fixed it temporarily but today I had a massive memory leak with gw2.exe hitting 1 million K on task manager. I closed the game and then when I opened the client the error returned.