diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 51f68bb6bdb8..daa437df8115 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -1800,6 +1800,8 @@ chk_prio_nr()
 {
 	local mp_prio_nr_tx=$1
 	local mp_prio_nr_rx=$2
+	local mpj_syn=$3
+	local mpj_syn_ack=$4
 	local count
 	local dump_stats
 
@@ -1827,6 +1829,30 @@ chk_prio_nr()
 		echo "[ ok ]"
 	fi
 
+	printf "%-${nr_blank}s %s" " " "bkp syn"
+	count=$(get_counter ${ns1} "MPTcpExtMPJoinSynBackupRx")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" != "$mpj_syn" ]; then
+		echo "[fail] got $count JOIN[s] syn with Backup expected $mpj_syn"
+		fail_test
+		dump_stats=1
+	else
+		echo -n "[ ok ]"
+	fi
+
+	echo -n " - synack   "
+	count=$(get_counter ${ns2} "MPTcpExtMPJoinSynAckBackupRx")
+	if [ -z "$count" ]; then
+		echo "[skip]"
+	elif [ "$count" != "$mpj_syn_ack" ]; then
+		echo "[fail] got $count JOIN[s] synack with Backup expected $mpj_syn_ack"
+		fail_test
+		dump_stats=1
+	else
+		echo "[ ok ]"
+	fi
+
 	[ "${dump_stats}" = 1 ] && dump_stats
 }
 
@@ -2633,7 +2659,7 @@ backup_tests()
 		pm_nl_add_endpoint $ns2 10.0.3.2 flags subflow,backup
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow nobackup
 		chk_join_nr 1 1 1
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 1 0
 	fi
 
 	# single address, backup
@@ -2645,7 +2671,7 @@ backup_tests()
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow backup
 		chk_join_nr 1 1 1
 		chk_add_nr 1 1
-		chk_prio_nr 1 1
+		chk_prio_nr 1 1 0 0
 	fi
 
 	# single address with port, backup
@@ -2657,7 +2683,7 @@ backup_tests()
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow backup
 		chk_join_nr 1 1 1
 		chk_add_nr 1 1
-		chk_prio_nr 1 1
+		chk_prio_nr 1 1 0 0
 	fi
 
 	if reset "mpc backup" &&
@@ -2665,7 +2691,7 @@ backup_tests()
 		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow,backup
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
 		chk_join_nr 0 0 0
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 0 0
 	fi
 
 	if reset "mpc backup both sides" &&
@@ -2674,7 +2700,7 @@ backup_tests()
 		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow,backup
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
 		chk_join_nr 0 0 0
-		chk_prio_nr 1 1
+		chk_prio_nr 1 1 0 0
 	fi
 
 	if reset "mpc switch to backup" &&
@@ -2682,7 +2708,7 @@ backup_tests()
 		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow backup
 		chk_join_nr 0 0 0
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 0 0
 	fi
 
 	if reset "mpc switch to backup both sides" &&
@@ -2691,7 +2717,7 @@ backup_tests()
 		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow backup
 		chk_join_nr 0 0 0
-		chk_prio_nr 1 1
+		chk_prio_nr 1 1 0 0
 	fi
 }
 
@@ -3022,7 +3048,7 @@ fullmesh_tests()
 		pm_nl_set_limits $ns2 4 4
 		run_tests $ns1 $ns2 10.0.1.1 0 0 1 slow backup,fullmesh
 		chk_join_nr 2 2 2
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 1 0
 		chk_rm_nr 0 1
 	fi
 
@@ -3034,7 +3060,7 @@ fullmesh_tests()
 		pm_nl_add_endpoint $ns2 10.0.2.2 flags subflow,backup,fullmesh
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow nobackup,nofullmesh
 		chk_join_nr 2 2 2
-		chk_prio_nr 0 1
+		chk_prio_nr 0 1 1 0
 		chk_rm_nr 0 1
 	fi
 }
@@ -3140,7 +3166,7 @@ userspace_tests()
 		pm_nl_add_endpoint $ns2 10.0.3.2 flags subflow
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow backup
 		chk_join_nr 1 1 0
-		chk_prio_nr 0 0
+		chk_prio_nr 0 0 0 0
 	fi
 
 	# userspace pm type prevents rm_addr