Invalid Host header nodejs tunnel

Hello I have created a node js react app that I wish to run at home on my raspberry Pi.

I have added a tunnel that uses the pi’s ip and the port the server is on but when I go to my domain I get a Invalid Host Header error. I noticed that there is a host header option in the hostname settings but I am unsure of what it does.

You should check what host the application is expecting and make sure you are sending the correct header.