Proxy (an URL) via lighttpd to different http server

I’m trying to proxy a specific URL to another httpd. Is far I remember I got that working (~6 month) in the past, but actually it doesn’t work. Maybe this is related to the latest update of lighttpd, but I can’t verify this as old packages seems not available anymore.

# opkg list_installed | grep -E "mod\-(proxy|redirect)"
lighttpd-mod-proxy - 1.4.45-1
lighttpd-mod-redirect - 1.4.45-1
# cat /etc/lighttpd/conf.d/zzz_local.conf
$HTTP["url"] =~ "^/(test2)/" {
  proxy.server  = (
        ""    => (( "host" => ""))

$HTTP["url"] =~ "^/(test)/" {
  url.redirect  = (
      "^/test/(.*)" => "$1",

While /test2/ gives a “Error: 404 Not Found”, /test/ redirects fine to So this seems not a problem of the URL-condition. Even the proxy part works fine on another (debian based) system. I verified with tcpdump that there are no requests are send out to the backend server.
After debugging several hours I’m unable to trace the issue down. Even as lighttpd seems not to log something related into error log nor systemlog.

Help is appreciated, thanks.