Hello Eidan,
My advice would be to contact Blizzard Support.
Error 1016 is a generic error… it essentially means that you’ve lost connection to the server. It doesn’t say why nor where the error might be. Because it is a generic error, there isn’t a single solution to the issue… or issues (there may be several).
Give the game support system a try… not here on the forums but through a ticket.
Use the following link :
https://eu.battle.net/support/en/help/contact/277/ticket
and provide the information requested. The blue-coloured words are link to additional information or procedures to help you provide the information Blizzard needs to help you.
Solving this error may require more than one attempt… if the steps suggested by Blizzard do not solve the issue, reply and let them know.
Finally… do provide details of the troubleshooting you have already attempted… so they don’t ask you to do it again.
Good luck… bear in mind that, with COVID-19, the waiting time for a response will be longer than it would be normally.
Good luck with this.