Suedkiez
(Just a fellow user like you)
4
The server version in production is build 1401, which you have.
ARC in production is 1.0.50 (build 261):
ARC in Early Access / Beta is build 264, which seems to be what you have (as I made bold in your quote above):
So seems that you are trying to use ARC beta with a production server and hence you get the prompt to update your server.
The alternative is, of course, to revert your ARC to the production version.