How to setup a catch-all-router?

I want to setup several routers for handling my http/https traffic. Finally I want to setup an additional router which should cover all traffic which was not handled by a previous router/rule (forward to a default homepage). (How) Is this possible ?

This will really depend on the other router rules that you have.

Read over routers priority

You will now know that you can create a PathPrefix(`/`) rule with a set priority set to a low value of 1.

All your other routing rules would be processed before this one. Connect this router to a redirectRegex middleware