How to resolve the 403 error when creating a new node via RESTful module?
For headers you only need Content-Type and Authorization.

Your POST url needs to be http://fischer.dev:80/entity/node (this is only for POST).

If you are going to PATCH or DELETE, the url would then be the url of the node, Ex: http://fischer.dev:80/node/1 that you want to update (patch) or delete. 



PS: Not really sure why you have port numbers in your url, and why you were using port 81 instead of 80, using http://fischer.dev/entity/node should be good enough.