Trying to make a Signal bridge using Caddy webserver

Caddyfile

# Edit: this doesn't work, I can't get the upstream part to be "raw"
# Also this error: "http.request.tls.server_name" will be "signal.xn--sb-lka.org" and not the inner SNI

signal.xn--sb-lka.org {
    #respond / "HELLO"

    map {http.request.tls.server_name}  {my_placeholder} {
        chat.signal.org                        "chat.signal.org:443"
        ud-chat.signal.org                     "chat.signal.org:443"
        textsecure-service.whispersystems.org  "chat.signal.org:443"
        storage.signal.org                     "storage.signal.org:443"
        cdn.signal.org                         "cdn.signal.org:443"
        cdn2.signal.org                        "cdn2.signal.org:443"
        api.directory.signal.org               "api.directory.signal.org:443"
        cdsi.signal.org                        "cdsi.signal.org:443"
        contentproxy.signal.org                "contentproxy.signal.org:443"
        uptime.signal.org                      "uptimesignal.org:443"
        api.backup.signal.org                  "api.backup.signal.org:443"
        sfu.voip.signal.org                    "sfu.voip.signal.org:443"
        updates.signal.org                     "updates.signal.org:443"
        updates2.signal.org                    "updates2.signal.org:443"
        # ~(.*)\.example\.com$                 "${1}.signal.org:443"
        default                                "127.0.0.1:1234"
    }
    #reverse_proxy {my_placeholder}
    reverse_proxy {
        to {my_placeholder}
        transport http {
            tls
            tls_insecure_skip_verify
            tls_server_name {my_placeholder}
        }
    }
}