Resource Root Url 404 error

I am using Jenkins version 2.414.3 as docker image inside an ECS container and exposed via a private nlb(Network Load balancer) with custom domain name, so that this can only be accessed via our company vpn. Recently I was trying to implement resource url to serve html reports generated by my jenkins build. I usually send them as files to slack. Now looking to send it as url, I’ve tried the documentation and tried to add a new hostname for resource root url( that points to the same nlb with a change in subdomain name, Now when I try to access my artifact it is redirecting to this root url. The redirecting url seems like$TOKEN/report.html but it is giving 404 Not found error on servelet Stapler. Please help me resolve this

NB: Also is there a way to get the reosurce root url for each artifacts, so that I can send it along my slack notification.