diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index b48b4e56826a9..5e3c56253274a 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -137,7 +137,7 @@ TEST_GROUP=""
 #shellcheck disable=SC2317
 cleanup()
 {
-	rm -f "$cin_disconnect" "$cout_disconnect"
+	rm -f "$cin_disconnect"
 	rm -f "$cin" "$cout"
 	rm -f "$sin" "$sout"
 	rm -f "$capout"
@@ -155,7 +155,6 @@ cin=$(mktemp)
 cout=$(mktemp)
 capout=$(mktemp)
 cin_disconnect="$cin".disconnect
-cout_disconnect="$cout".disconnect
 trap cleanup EXIT
 
 mptcp_lib_ns_init ns1 ns2 ns3 ns4
@@ -445,12 +444,8 @@ do_transfer()
 	printf "(duration %05sms) " "${duration}"
 	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ]; then
 		mptcp_lib_pr_fail "client exit code $retc, server $rets"
-		echo -e "\nnetns ${listener_ns} socket stat for ${port}:" 1>&2
-		ip netns exec ${listener_ns} ss -Menita 1>&2 -o "sport = :$port"
-		cat /tmp/${listener_ns}.out
-		echo -e "\nnetns ${connector_ns} socket stat for ${port}:" 1>&2
-		ip netns exec ${connector_ns} ss -Menita 1>&2 -o "dport = :$port"
-		[ ${listener_ns} != ${connector_ns} ] && cat /tmp/${connector_ns}.out
+		mptcp_lib_pr_err_stats "${listener_ns}" "${connector_ns}" "${port}" \
+			"/tmp/${listener_ns}.out" "/tmp/${connector_ns}.out"
 
 		echo
 		cat "$capout"
@@ -587,7 +582,7 @@ make_file()
 	mptcp_lib_make_file $name 1024 $ksize
 	dd if=/dev/urandom conv=notrunc of="$name" oflag=append bs=1 count=$rem 2> /dev/null
 
-	echo "Created $name (size $(du -b "$name")) containing data sent by $who"
+	echo "Created $name (size $(stat -c "%s" "$name") B) containing data sent by $who"
 }
 
 run_tests_lo()
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index c07e2bd3a315a..13a3b68181ee1 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -1039,13 +1039,8 @@ do_transfer()
 
 	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ]; then
 		fail_test "client exit code $retc, server $rets"
-		echo -e "\nnetns ${listener_ns} socket stat for ${port}:" 1>&2
-		ip netns exec ${listener_ns} ss -Menita 1>&2 -o "sport = :$port"
-		cat /tmp/${listener_ns}.out
-		echo -e "\nnetns ${connector_ns} socket stat for ${port}:" 1>&2
-		ip netns exec ${connector_ns} ss -Menita 1>&2 -o "dport = :$port"
-		cat /tmp/${connector_ns}.out
-
+		mptcp_lib_pr_err_stats "${listener_ns}" "${connector_ns}" "${port}" \
+			"/tmp/${listener_ns}.out" "/tmp/${connector_ns}.out"
 		return 1
 	fi
 
diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
index 975d4d4c862af..051e289d79676 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -107,6 +107,27 @@ mptcp_lib_pr_info() {
 	mptcp_lib_print_info "INFO: ${*}"
 }
 
+# $1-2: listener/connector ns ; $3 port ; $4-5 listener/connector stat file
+mptcp_lib_pr_err_stats() {
+	local lns="${1}"
+	local cns="${2}"
+	local port="${3}"
+	local lstat="${4}"
+	local cstat="${5}"
+
+	echo -en "${MPTCP_LIB_COLOR_RED}"
+	{
+		printf "\nnetns %s (listener) socket stat for %d:\n" "${lns}" "${port}"
+		ip netns exec "${lns}" ss -Menitam -o "sport = :${port}"
+		cat "${lstat}"
+
+		printf "\nnetns %s (connector) socket stat for %d:\n" "${cns}" "${port}"
+		ip netns exec "${cns}" ss -Menitam -o "dport = :${port}"
+		[ "${lstat}" != "${cstat}" ] && cat "${cstat}"
+	} 1>&2
+	echo -en "${MPTCP_LIB_COLOR_RESET}"
+}
+
 # SELFTESTS_MPTCP_LIB_EXPECT_ALL_FEATURES env var can be set when validating all
 # features using the last version of the kernel and the selftests to make sure
 # a test is not being skipped by mistake.
diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
index 5e8d5b83e2d09..418a903c3a4d3 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
@@ -169,6 +169,11 @@ do_transfer()
 		cmsg+=",TCPINQ"
 	fi
 
+	NSTAT_HISTORY=/tmp/${listener_ns}.nstat ip netns exec ${listener_ns} \
+		nstat -n
+	NSTAT_HISTORY=/tmp/${connector_ns}.nstat ip netns exec ${connector_ns} \
+		nstat -n
+
 	timeout ${timeout_test} \
 		ip netns exec ${listener_ns} \
 			$mptcp_connect -t ${timeout_poll} -l -M 1 -p $port -s ${srv_proto} -c "${cmsg}" \
@@ -189,14 +194,16 @@ do_transfer()
 	wait $spid
 	local rets=$?
 
+	NSTAT_HISTORY=/tmp/${listener_ns}.nstat ip netns exec ${listener_ns} \
+		nstat | grep Tcp > /tmp/${listener_ns}.out
+	NSTAT_HISTORY=/tmp/${connector_ns}.nstat ip netns exec ${connector_ns} \
+		nstat | grep Tcp > /tmp/${connector_ns}.out
+
 	print_title "Transfer ${ip:2}"
 	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ]; then
 		mptcp_lib_pr_fail "client exit code $retc, server $rets"
-		echo -e "\nnetns ${listener_ns} socket stat for ${port}:" 1>&2
-		ip netns exec ${listener_ns} ss -Menita 1>&2 -o "sport = :$port"
-
-		echo -e "\nnetns ${connector_ns} socket stat for ${port}:" 1>&2
-		ip netns exec ${connector_ns} ss -Menita 1>&2 -o "dport = :$port"
+		mptcp_lib_pr_err_stats "${listener_ns}" "${connector_ns}" "${port}" \
+			"/tmp/${listener_ns}.out" "/tmp/${connector_ns}.out"
 
 		mptcp_lib_result_fail "transfer ${ip}"
 
diff --git a/tools/testing/selftests/net/mptcp/simult_flows.sh b/tools/testing/selftests/net/mptcp/simult_flows.sh
index 8fa77c8e9b651..9c2a415976cbf 100755
--- a/tools/testing/selftests/net/mptcp/simult_flows.sh
+++ b/tools/testing/selftests/net/mptcp/simult_flows.sh
@@ -155,6 +155,11 @@ do_transfer()
 		sleep 1
 	fi
 
+	NSTAT_HISTORY=/tmp/${ns3}.nstat ip netns exec ${ns3} \
+		nstat -n
+	NSTAT_HISTORY=/tmp/${ns1}.nstat ip netns exec ${ns1} \
+		nstat -n
+
 	timeout ${timeout_test} \
 		ip netns exec ${ns3} \
 			./mptcp_connect -jt ${timeout_poll} -l -p $port -T $max_time \
@@ -180,25 +185,27 @@ do_transfer()
 		kill ${cappid_connector}
 	fi
 
+	NSTAT_HISTORY=/tmp/${ns3}.nstat ip netns exec ${ns3} \
+		nstat | grep Tcp > /tmp/${ns3}.out
+	NSTAT_HISTORY=/tmp/${ns1}.nstat ip netns exec ${ns1} \
+		nstat | grep Tcp > /tmp/${ns1}.out
+
 	cmp $sin $cout > /dev/null 2>&1
 	local cmps=$?
 	cmp $cin $sout > /dev/null 2>&1
 	local cmpc=$?
 
-	printf "%-16s" " max $max_time "
 	if [ $retc -eq 0 ] && [ $rets -eq 0 ] && \
 	   [ $cmpc -eq 0 ] && [ $cmps -eq 0 ]; then
+		printf "%-16s" " max $max_time "
 		mptcp_lib_pr_ok
 		cat "$capout"
 		return 0
 	fi
 
-	mptcp_lib_pr_fail
-	echo "client exit code $retc, server $rets" 1>&2
-	echo -e "\nnetns ${ns3} socket stat for $port:" 1>&2
-	ip netns exec ${ns3} ss -nita 1>&2 -o "sport = :$port"
-	echo -e "\nnetns ${ns1} socket stat for $port:" 1>&2
-	ip netns exec ${ns1} ss -nita 1>&2 -o "dport = :$port"
+	mptcp_lib_pr_fail "client exit code $retc, server $rets"
+	mptcp_lib_pr_err_stats "${ns3}" "${ns1}" "${port}" \
+		"/tmp/${ns3}.out" "/tmp/${ns1}.out"
 	ls -l $sin $cout
 	ls -l $cin $sout