diff --git a/tests/lz4-compression b/tests/lz4-compression
index ccf0621f..f9d9d63a 100755
--- a/tests/lz4-compression
+++ b/tests/lz4-compression
@@ -43,7 +43,7 @@ if test "$(id -u)" != "0";then
 	exit 77
 fi
 
-echo "Testing ocserv connection via haproxy... "
+echo "Testing LZ4 compression... "
 
 function finish {
   set +e
@@ -104,13 +104,16 @@ ${CMDNS1} iperf3 -t 6 -c ${VPNADDR}
 
 # IPv6
 
-${CMDNS2} iperf3 -s -D -1
+# iperf3 might not release the port immediately; get an alternative port
+set +e; eval "${GETPORT}"; set -e
+
+${CMDNS2} iperf3 -s -D -1 -p ${PORT}
 
 ${CMDNS1} ping -6 -c 3 ${VPNADDR6}
 
 echo " * Receiving with iperf3"
 
-${CMDNS1} iperf3 -t 6 -R -c ${VPNADDR}
+${CMDNS1} iperf3 -t 6 -R -c ${VPNADDR} -p ${PORT}
 
 set +e
 
diff --git a/tests/lzs-compression b/tests/lzs-compression
index 3277b2a6..8bf6ce6c 100755
--- a/tests/lzs-compression
+++ b/tests/lzs-compression
@@ -43,7 +43,7 @@ if test "$(id -u)" != "0";then
 	exit 77
 fi
 
-echo "Testing ocserv connection via haproxy... "
+echo "Testing LZS compression... "
 
 function finish {
   set +e
@@ -104,13 +104,16 @@ ${CMDNS1} iperf3 -t 6 -c ${VPNADDR}
 
 # IPv6
 
-${CMDNS2} iperf3 -s -D -1
+# iperf3 might not release the port immediately; get an alternative port
+set +e; eval "${GETPORT}"; set -e
+
+${CMDNS2} iperf3 -s -D -1 -p ${PORT}
 
 ${CMDNS1} ping -6 -c 3 ${VPNADDR6}
 
 echo " * Receiving with iperf3"
 
-${CMDNS1} iperf3 -t 6 -R -c ${VPNADDR}
+${CMDNS1} iperf3 -t 6 -R -c ${VPNADDR} -p ${PORT}
 
 set +e
 
diff --git a/tests/traffic b/tests/traffic
index b85a74ee..cff18733 100755
--- a/tests/traffic
+++ b/tests/traffic
@@ -41,7 +41,7 @@ if test "$(id -u)" != "0";then
 	exit 77
 fi
 
-echo "Testing ocserv connection via haproxy... "
+echo "Testing ocserv traffic... "
 
 function finish {
   set +e
@@ -100,10 +100,12 @@ echo " * Transmitting with iperf3"
 
 ${CMDNS1} iperf3 -t 6 -c ${VPNADDR}
 
-${CMDNS2} iperf3 -s -D -1
+# iperf3 might not release the port immediately; get an alternative port
+set +e; eval "${GETPORT}"; set -e
 
+${CMDNS2} iperf3 -s -D -1 -p ${PORT}
 
-${CMDNS1} iperf3 -t 6 -R -c ${VPNADDR}
+${CMDNS1} iperf3 -t 6 -R -c ${VPNADDR} -p ${PORT}
 
 echo " * ping ipv6 address"