Why world boss chest disappears? :/
The chest disappears after about 5 minutes. If you can’t loot it and you are suffering a lot of lag, it might be that you aren’t getting participation credit. When there’s latency between your computer and the server, you will sometimes think you are doing more damage than you really are.
Since GW2 doesn’t actually require “high speed” (just faster than dial-up), there might be something else going on with your connection. You can work with Customer Service to see if they can help you track it down.
The other thing that will help is to join a party, so that you don’t have to do as much damage to get credit.
I live in Australia and get such bad lag in GW2 (spikes of up to 3000ms+ that world bosses are basically unplayable (along with any other content where there are large groups of people) and the client frequently crashes at the end meaning I get no credit for the daily even though I have done damage and no chest. Also it is NOT my internet connection or ISP, I have a good quality connection and play other MMO’s perfectly fine on EU and US servers. I am playing on EU at the moment and my ping is usually over 500 and I can’t even test it out on the NA server without having to fork out for a transfer which may or may not be effective. Unfortunately you may just have to endure this as I am yet to find a solution, other than to move country