I think in this case another HTTP route without “www” is needed.
Check the current HTTP route for lamp to get the URL:
Create a HTTP route without the www part as Host, using the URL from the previous step and enable Lets Encrypt to get a valid certificate.
Now both hostnames with and without www should redirect to the web page.
EDIT:
It seems you’re using an older version of lamp. It was moved to NethForge repository, see Request to join Nethforge for ns8-lamp
Maybe you need to enable the repo to get updates for lamp.

