I have two RB951Ui-2HnD running 6.4 I'm using to trial for our staff housing (each house has an internet connection) but I've gotten universal feedback of poor wireless performance compared with our old cheap and nasty TP-Link wireless routers.
Setup is fairly simple, Mikrotik acts as a PPPoE client through the ISP provided bridge equipment and provides wireless access to the people in the household (802.11b/g/n 20/40MHz, WPA2 AES). The surrounding air is fairly quiet (Only about 3 other SSIDs in the area) and noise floor is -101, client get between -40 and -70 but at the very most get Rx speeds of 72Mbps with Tx speeds usually around 1Mbps. Devices consist of a variety of phones and laptops, all have the same issue (No Macbooks though). About 5 to 10 devices are connected to the AP at any one time. One user reported they couldn't even connect with their laptop.
Don't have access to the unit at the moment (so no screenshots or config) but wireless settings are basically unchanged since factory then upgrade. I've got some scripts running (CPU and RAM usage are fine) and simple queues (for statistics only, no throttling) but the performance problems occur before those stages.
Does anyone have any general Mikrotik performance tuning or wireless debugging advise?