WAVLINK WL-WN577A2 / Maginon WL-755AC regulary crashes under heavy load

I think it would be best to seperate this issue from my MT7620A post.

Why does the 'WAVLINK WL-WN577A2 / Maginon WL-755AC' sometimes crash under heavy load?

I tested it yesterday with the latest snapshot installed and it worked flawless for hours with iperf -d stressing providing superb signal strenght and constant 100Mbit/s - the same evening it crashed just after some minutes video 'streaming' (more a dia-show!) and transmission speed was about 30Mbit/s only.

I really would love to use this device again as it consumes about 2 watts power only (less than 1 watt in idle).

Today I tested again:

$ iperf -c odu3p -t 300 -i 5 -d
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size:  128 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to odu3p, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  4] local 192.168.200.208 port 54914 connected with 192.168.200.13 port 5001
[  5] local 192.168.200.208 port 5001 connected with 192.168.200.13 port 51050
[ ID] Interval       Transfer     Bandwidth
[  5]  0.0- 5.0 sec  6.41 MBytes  10.7 Mbits/sec
[  4]  0.0- 5.0 sec  31.1 MBytes  52.2 Mbits/sec
[  5]  5.0-10.0 sec  2.70 MBytes  4.52 Mbits/sec
[  4]  5.0-10.0 sec  33.8 MBytes  56.6 Mbits/sec
[  5] 10.0-15.0 sec  8.60 MBytes  14.4 Mbits/sec
[  4] 10.0-15.0 sec  29.6 MBytes  49.7 Mbits/sec
[  4] 15.0-20.0 sec  25.2 MBytes  42.4 Mbits/sec
[  5] 15.0-20.0 sec  13.7 MBytes  23.0 Mbits/sec
[  4] 20.0-25.0 sec  13.5 MBytes  22.7 Mbits/sec
[  5] 20.0-25.0 sec  5.73 MBytes  9.62 Mbits/sec
[  4] 25.0-30.0 sec  0.00 Bytes  0.00 bits/sec
[  5] 25.0-30.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 30.0-35.0 sec  0.00 Bytes  0.00 bits/sec
[  5] 30.0-35.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 35.0-40.0 sec  0.00 Bytes  0.00 bits/sec
[  5] 35.0-40.0 sec  0.00 Bytes  0.00 bits/sec
[  4] 40.0-45.0 sec  0.00 Bytes  0.00 bits/sec
[  5] 40.0-45.0 sec  0.00 Bytes  0.00 bits/sec

Had to power-cycle router to make it work again.
Router and client stand right beside each other!
Thank you in advance;
Gerry