Just to try an additional help, in case it has somehow affected your PC:
In the Menu Configurations there is a timer that shuts down your game after 30 minutes of inactivity/input UNLESS you have turned that off. Is that turned back on somehow, or affecting your playtime? Because if it is and you go AFK bazaaring or just chatting, it will d/c off your character. Exactly at 30 minutes. I know it's weird and you may have turned it off or are not afk, but couldn't hurt to check.