Just to recap some information
the error router_deployment_not_found is not the issue. It is a symptom of the deployment not syncing up correctly. Webinterface/Cloud (NOT selfhosted) a lot of times seems to be using an up-to-date deployment whereas accessing it via URL accesses an older deplyoment (which in my case, when trying to figure this out, resulted to this error after deleting all deployments and pushing a new one).
I can rule out caching because when i add a log or a table insert or something, it will do that using the execution function on the dashboard but not via url.