diff --git a/lib/misc/peer-limits.c b/lib/misc/peer-limits.c
index 707454fe..2fcb8bb8 100644
--- a/lib/misc/peer-limits.c
+++ b/lib/misc/peer-limits.c
@@ -248,7 +248,9 @@ lws_peer_track_ah_detach(struct lws_context *context, struct lws_peer *peer)
 	if (!peer)
 		return;
 
+	lws_context_lock(context); /* <====================================== */
 	assert(peer->count_ah);
 	peer->count_ah--;
+	lws_context_unlock(context); /* ====================================> */
 }
 
diff --git a/lib/private-libwebsockets.h b/lib/private-libwebsockets.h
index c6ab7539..965da436 100644
--- a/lib/private-libwebsockets.h
+++ b/lib/private-libwebsockets.h
@@ -1675,7 +1675,7 @@ lws_client_reset(struct lws **wsi, int ssl, const char *address, int port,
 		 const char *path, const char *host);
 
 LWS_EXTERN struct lws * LWS_WARN_UNUSED_RESULT
-lws_create_new_server_wsi(struct lws_vhost *vhost);
+lws_create_new_server_wsi(struct lws_vhost *vhost, int fixed_tsi);
 
 LWS_EXTERN char * LWS_WARN_UNUSED_RESULT
 lws_generate_client_handshake(struct lws *wsi, char *pkt);
diff --git a/lib/roles/h2/http2.c b/lib/roles/h2/http2.c
index 69e248b8..b0a45578 100644
--- a/lib/roles/h2/http2.c
+++ b/lib/roles/h2/http2.c
@@ -175,7 +175,7 @@ lws_wsi_server_new(struct lws_vhost *vh, struct lws *parent_wsi,
 		lwsl_notice("reached concurrent stream limit\n");
 		return NULL;
 	}
-	wsi = lws_create_new_server_wsi(vh);
+	wsi = lws_create_new_server_wsi(vh, parent_wsi->tsi);
 	if (!wsi) {
 		lwsl_notice("new server wsi failed (vh %p)\n", vh);
 		return NULL;
diff --git a/lib/roles/http/server/parsers.c b/lib/roles/http/server/parsers.c
index 4546cefd..67c8dd60 100644
--- a/lib/roles/http/server/parsers.c
+++ b/lib/roles/http/server/parsers.c
@@ -298,8 +298,7 @@ int __lws_header_table_detach(struct lws *wsi, int autoservice)
 		 * unreasonably long time
 		 */
 		lwsl_debug("%s: wsi %p: ah held %ds, role/state 0x%x 0x%x,"
-			    "\n", __func__, wsi,
-			    (int)(now - ah->assigned),
+			    "\n", __func__, wsi, (int)(now - ah->assigned),
 			    lwsi_role(wsi), lwsi_state(wsi));
 	}
 
@@ -310,10 +309,12 @@ int __lws_header_table_detach(struct lws *wsi, int autoservice)
 	/* and this specific one should have been in use */
 	assert(ah->in_use);
 	memset(&wsi->ah, 0, sizeof(wsi->ah));
-	ah->wsi = NULL; /* no owner */
+
 #if defined(LWS_WITH_PEER_LIMITS)
-	lws_peer_track_ah_detach(context, wsi->peer);
+	if (ah->wsi)
+		lws_peer_track_ah_detach(context, wsi->peer);
 #endif
+	ah->wsi = NULL; /* no owner */
 
 	pwsi = &pt->ah_wait_list;
 
@@ -357,8 +358,10 @@ int __lws_header_table_detach(struct lws *wsi, int autoservice)
 
 	__lws_header_table_reset(wsi, autoservice);
 #if defined(LWS_WITH_PEER_LIMITS)
+	lws_context_lock(context); /* <====================================== */
 	if (wsi->peer)
 		wsi->peer->count_ah++;
+	lws_context_unlock(context); /* ====================================> */
 #endif
 
 	/* clients acquire the ah and then insert themselves in fds table... */
diff --git a/lib/roles/http/server/server.c b/lib/roles/http/server/server.c
index d4ec9ebc..fac864e7 100644
--- a/lib/roles/http/server/server.c
+++ b/lib/roles/http/server/server.c
@@ -1644,10 +1644,13 @@ lws_get_idlest_tsi(struct lws_context *context)
 }
 
 struct lws *
-lws_create_new_server_wsi(struct lws_vhost *vhost)
+lws_create_new_server_wsi(struct lws_vhost *vhost, int fixed_tsi)
 {
 	struct lws *new_wsi;
-	int n = lws_get_idlest_tsi(vhost->context);
+	int n = fixed_tsi;
+
+	if (n < 0)
+		n = lws_get_idlest_tsi(vhost->context);
 
 	if (n < 0) {
 		lwsl_err("no space for new conn\n");
@@ -1840,7 +1843,10 @@ lws_adopt_descriptor_vhost(struct lws_vhost *vh, lws_adoption_type type,
 	}
 #endif
 
-	new_wsi = lws_create_new_server_wsi(vh);
+	n = -1;
+	if (parent)
+		n = parent->tsi;
+	new_wsi = lws_create_new_server_wsi(vh, n);
 	if (!new_wsi) {
 		if (type & LWS_ADOPT_SOCKET && !(type & LWS_ADOPT_WS_PARENTIO))
 			compatible_close(fd.sockfd);