local stat_ackrx_now_l=$(get_mib_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
        local stat_cookietx_now=$(get_mib_counter "${listener_ns}" "TcpExtSyncookiesSent")
        local stat_cookierx_now=$(get_mib_counter "${listener_ns}" "TcpExtSyncookiesRecv")
+       local stat_ooo_now=$(get_mib_counter "${listener_ns}" "TcpExtTCPOFOQueue")
 
        expect_synrx=$((stat_synrx_last_l))
        expect_ackrx=$((stat_ackrx_last_l))
                        "${stat_synrx_now_l}" "${expect_synrx}" 1>&2
                retc=1
        fi
-       if [ ${stat_ackrx_now_l} -lt ${expect_ackrx} ]; then
-               printf "[ FAIL ] lower MPC ACK rx (%d) than expected (%d)\n" \
-                       "${stat_ackrx_now_l}" "${expect_ackrx}" 1>&2
-               rets=1
+       if [ ${stat_ackrx_now_l} -lt ${expect_ackrx} -a ${stat_ooo_now} -eq 0 ]; then
+               if [ ${stat_ooo_now} -eq 0 ]; then
+                       printf "[ FAIL ] lower MPC ACK rx (%d) than expected (%d)\n" \
+                               "${stat_ackrx_now_l}" "${expect_ackrx}" 1>&2
+                       rets=1
+               else
+                       printf "[ Note ] fallback due to TCP OoO"
+               fi
        fi
 
        if [ $retc -eq 0 ] && [ $rets -eq 0 ]; then