diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index cf21b5e40a..d564d8d234 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -413,7 +413,8 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict)
         goto exit;
     }
 
-    nbd_server_start(addr, NULL, NULL, 0, &local_err);
+    nbd_server_start(addr, NULL, NULL, NBD_DEFAULT_MAX_CONNECTIONS,
+                     &local_err);
     qapi_free_SocketAddress(addr);
     if (local_err != NULL) {
         goto exit;
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index bf02ddc1e0..b357ae9bf1 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -170,6 +170,10 @@ void nbd_server_start(SocketAddress *addr, const char *tls_creds,
 
 void nbd_server_start_options(NbdServerOptions *arg, Error **errp)
 {
+    if (!arg->has_max_connections) {
+        arg->max_connections = NBD_DEFAULT_MAX_CONNECTIONS;
+    }
+
     nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz,
                      arg->max_connections, errp);
 }
@@ -182,6 +186,10 @@ void qmp_nbd_server_start(SocketAddressLegacy *addr,
 {
     SocketAddress *addr_flat = socket_address_flatten(addr);
 
+    if (!has_max_connections) {
+        max_connections = NBD_DEFAULT_MAX_CONNECTIONS;
+    }
+
     nbd_server_start(addr_flat, tls_creds, tls_authz, max_connections, errp);
     qapi_free_SocketAddress(addr_flat);
 }
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 3392a5c319..88be104e31 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -33,6 +33,13 @@ extern const BlockExportDriver blk_exp_nbd;
  */
 #define NBD_DEFAULT_HANDSHAKE_MAX_SECS 10
 
+/*
+ * NBD_DEFAULT_MAX_CONNECTIONS: Number of client sockets to allow at
+ * once; must be large enough to allow a MULTI_CONN-aware client like
+ * nbdcopy to create its typical number of 8-16 sockets.
+ */
+#define NBD_DEFAULT_MAX_CONNECTIONS 100
+
 /* Handshake phase structs - this struct is passed on the wire */
 
 struct NBDOption {
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 4627bbc4e6..67d2337f91 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -24,7 +24,7 @@
 # @max-connections: The maximum number of connections to allow at the same
 #                   time, 0 for unlimited. Setting this to 1 also stops
 #                   the server from advertising multiple client support
-#                   (since 5.2; default: 0)
+#                   (since 5.2; default: 100)
 #
 # Since: 4.2
 ##
@@ -55,7 +55,7 @@
 # @max-connections: The maximum number of connections to allow at the same
 #                   time, 0 for unlimited. Setting this to 1 also stops
 #                   the server from advertising multiple client support
-#                   (since 5.2; default: 0).
+#                   (since 5.2; default: 100).
 #
 # Returns: error if the server is already running.
 #