diff --git a/conf/frpc_full_example.toml b/conf/frpc_full_example.toml
index 5a414137..ffa10ab6 100644
--- a/conf/frpc_full_example.toml
+++ b/conf/frpc_full_example.toml
@@ -133,7 +133,9 @@ transport.tls.enable = true
 # transport.tls.disableCustomTLSFirstByte = true
 
 # Heartbeat configure, it's not recommended to modify the default value.
-# The default value of heartbeatInterval is 10 and heartbeatTimeout is 90. Set negative value
+# If tcpMux is enabled (default), heartbeat is disabled and tcp mux keepalive
+# interval controls the liveness detection instead.
+# The default value of heartbeatInterval is 30 and heartbeatTimeout is 90. Set negative value
 # to disable it.
 # transport.heartbeatInterval = 30
 # transport.heartbeatTimeout = 90
diff --git a/conf/frps_full_example.toml b/conf/frps_full_example.toml
index aba37435..b66d2aa2 100644
--- a/conf/frps_full_example.toml
+++ b/conf/frps_full_example.toml
@@ -22,7 +22,9 @@ kcpBindPort = 7000
 # transport.quic.maxIdleTimeout = 30
 # transport.quic.maxIncomingStreams = 100000
 
-# Heartbeat configure, it's not recommended to modify the default value
+# Heartbeat configure, it's not recommended to modify the default value.
+# If tcpMux is enabled (default), heartbeat is disabled and tcp mux keepalive
+# interval controls the liveness detection instead.
 # The default value of heartbeatTimeout is 90. Set negative value to disable it.
 # transport.heartbeatTimeout = 90
 
diff --git a/pkg/config/v1/client.go b/pkg/config/v1/client.go
index bb95b6cd..a6e67bb1 100644
--- a/pkg/config/v1/client.go
+++ b/pkg/config/v1/client.go
@@ -133,6 +133,8 @@ type ClientTransportConfig struct {
 	// HeartBeatTimeout specifies the maximum allowed heartbeat response delay
 	// before the connection is terminated, in seconds. It is not recommended
 	// to change this value. By default, this value is 90. Set negative value to disable it.
+	// Note: When TCPMux is enabled (default), heartbeat checks are disabled and
+	// the TCP mux keepalive interval controls liveness instead.
 	HeartbeatTimeout int64 `json:"heartbeatTimeout,omitempty"`
 	// TLS specifies TLS settings for the connection to the server.
 	TLS TLSClientConfig `json:"tls,omitempty"`
diff --git a/pkg/config/v1/server.go b/pkg/config/v1/server.go
index a92aac97..90462f40 100644
--- a/pkg/config/v1/server.go
+++ b/pkg/config/v1/server.go
@@ -172,6 +172,8 @@ type ServerTransportConfig struct {
 	// HeartBeatTimeout specifies the maximum time to wait for a heartbeat
 	// before terminating the connection. It is not recommended to change this
 	// value. By default, this value is 90. Set negative value to disable it.
+	// Note: When TCPMux is enabled (default), heartbeat checks are disabled and
+	// the TCP mux keepalive interval controls liveness instead.
 	HeartbeatTimeout int64 `json:"heartbeatTimeout,omitempty"`
 	// QUIC options.
 	QUIC QUICOptions `json:"quic,omitempty"`