I believe that the dashboard has a upload limit of 50 MB, while the in game method using Dropbox is more efficient and has a 500 MB limit. The size of the world could be what's causing it.
Force a full server reset if the server wont start up. If it's just your client lagging when you try to join, reset the world. Not much of anything else you can do. Maybe try /kill @e[type=item] in console when your server is up.
ProtocolSupport is a plugin on Minehut that can be used to join older versions of Minecraft on to your server. I believe that works. If you have future questions related to Minehut join the discord or ask in the Help category!
Maybe Minehut so happens to have a way of stopping it or perhaps it's just what Minehut up runs on and is made up of. If you have any further questions ask in Help if related to Minehut.
If you are willing to take the risk, start your server and run /minecraft:kill @e[type=item] in the server console, then connect. I believe that's a command.