Situation (in basic/short - maybe little too basic):
4 WLAN's deployed. About 20AP's (different models).
R710 controlled by ZD 1200 - everything related UL/DL speed seems to be fine from client perspective (different laptops). Did some basic test using "speedtest.net" DL/UL is about around 140Mbit which is expected since our ISP gives us 150Mbps uplink.
Then I replaced R710 -> R720 and some weirdness begins - DL is ~140Mbps which is okay but UL is about 1....6Mbps!!!
Checked cabling, tried different PoE adapters, tried different switch ports, tried another R720, tried some other various possibilities - nothing.
Only thing that I'v noticed that makes some kind of difference is when I strart playing with "SSID Rate Limiting".
When the problem starts, there were no rate limiting on this particular WLAN, but when I set rate limiting to 200Mbps UL/DL, then testing against "speedtest.net" gives us about 80Mbps UL/DL (varies per test).
Also, there were some changes in UL/DL speed on this particular WLAN when I played with rate limiting on another WLAN - I don't understand how this is possible,but it was.
Since I had limited time to test further, I'v sent this R720 back to our reseller and continued with R710.
But I know that I should extend our WIFI infrastructure in near future, so I'm looking for recommendations what else should I do to find out what might be wrong?
BTW: On the time of problem, ZD FW update from 10.1.1.0.35 to 10.1.1.0.55 did not help.