I can't get to the route map localhost:8888 and it showed 404 error.
This only occurs while I am in the game.
When I quit, the webpage changes into 'connection refused'

Big thanks to help solving the problem!

by the way, I'm using Forge and Architectury

Ah yes, sorry; it is a bit different for the mod's forge port.

Localhost:8888 is only for the fabric port; but for forge; place this -

http://localhost:8888/index.html.

index.html was added at the end. Thanks.

Thanks!