diff --git a/README.md b/README.md
index fe65135..2494775 100644
--- a/README.md
+++ b/README.md
@@ -162,9 +162,17 @@ Headscale can be configured to expose its web service via TLS. To configure the
     "tls_letsencrypt_challenge_type": "HTTP-01",
 ```
 
-To get a certificate automatically via [Let's Encrypt](https://letsencrypt.org/), set `tls_letsencrypt_hostname` to the desired certificate hostname. This name must resolve to the IP address(es) Headscale is reachable on (i.e., it must correspond to the `server_url` configuration parameter). The certificate and Let's Encrypt account credentials will be stored in the directory configured in `tls_letsencrypt_cache_dir`. If the path is relative, it will be interpreted as relative to the directory the configuration file was read from. The certificate will automatically be renewed as needed. The default challenge type HTTP-01 requires that Headscale listens on port 80 for the Let's Encrypt automated validation, in addition to whatever port is configured in `listen_addr`. Alternatively, `tls_letsencrypt_challenge_type` can be set to `TLS-ALPN-01`. In this configuration, Headscale must be reachable via port 443, but port 80 is not required.
+To get a certificate automatically via [Let's Encrypt](https://letsencrypt.org/), set `tls_letsencrypt_hostname` to the desired certificate hostname. This name must resolve to the IP address(es) Headscale is reachable on (i.e., it must correspond to the `server_url` configuration parameter). The certificate and Let's Encrypt account credentials will be stored in the directory configured in `tls_letsencrypt_cache_dir`. If the path is relative, it will be interpreted as relative to the directory the configuration file was read from. The certificate will automatically be renewed as needed.
 
-If you need to change the ip/port used for the Let's Encrypt process, set `tls_letsencrypt_listen` to the appropriate value. This can be handy if you are running `headscale` as non-root (or can't run `setcap`). Keep in mind, however, Let's Encrypt will _only_ connect to port 80, so if you change `tls_letsencrypt_listen` you will also need to configure something else to send the traffic to the port you specify!
+#### Challenge type HTTP-01
+
+The default challenge type `HTTP-01` requires that Headscale is reachable on port 80 for the Let's Encrypt automated validation, in addition to whatever port is configured in `listen_addr`. By default, Headscale listens on port 80 on all local IPs for Let's Encrypt automated validation.
+
+If you need to change the ip and/or port used by Headscale for the Let's Encrypt validation process, set `tls_letsencrypt_listen` to the appropriate value. This can be handy if you are running Headscale as a non-root user (or can't run `setcap`). Keep in mind, however, that Let's Encrypt will _only_ connect to port 80 for the validation callback, so if you change `tls_letsencrypt_listen` you will also need to configure something else (e.g. a firewall rule) to forward the traffic from port 80 to the ip:port combination specified in `tls_letsencrypt_listen`.
+
+#### Challenge type TLS-ALPN-01
+
+Alternatively, `tls_letsencrypt_challenge_type` can be set to `TLS-ALPN-01`. In this configuration, Headscale listens on the ip:port combination defined in `listen_addr`. Let's Encrypt will _only_ connect to port 443 for the validation callback, so if `listen_addr` is not set to port 443, something else (e.g. a firewall rule) will be required to forward the traffic from port 443 to the ip:port combination specified in `listen_addr`.
 
 ### Policy ACLs
 
diff --git a/app.go b/app.go
index ab7b19b..fa9b011 100644
--- a/app.go
+++ b/app.go
@@ -165,7 +165,7 @@ func (h *Headscale) Serve() error {
 		if h.cfg.TLSLetsEncryptChallengeType == "TLS-ALPN-01" {
 			// Configuration via autocert with TLS-ALPN-01 (https://tools.ietf.org/html/rfc8737)
 			// The RFC requires that the validation is done on port 443; in other words, headscale
-			// must be configured to run on port 443.
+			// must be reachable on port 443.
 			err = s.ListenAndServeTLS("", "")
 		} else if h.cfg.TLSLetsEncryptChallengeType == "HTTP-01" {
 			// Configuration via autocert with HTTP-01. This requires listening on