The DYNSRV cookie is set by our hosting company, to stick you to a specific webserver - our website can be served by many different cloud servers.
We use Google Analytics. It sets the __umt cookies: https://developers.google.com/analytics/devguides/collection/analyticsjs/cookie-usage#gajs
The westlanUser cookie is used to track guests and authenticated users.
The Discord sidebar sets a couple of cookies for analytics and cross-site authentication purposes.