i do not understand how u can connect so many.
At my place i use 3 - base box on my tower and a few groove metal and some NS5. My basebox AP's cannot handle more than 10 clients and a total bandwidth of 6-8 mbps. Latency starts to go very high. I hv tried to lower data rates as per clients requirement and to maintain ccq. Noise floor is 110 dbm.
nv2 does the job very well. I have few APs where I have 20 clients on 802.11a on 3km distance. All of them are working on about 10Mbps together all time and when I'm at one of clints I can achieve around 12-15Mbps on speedtest. But sometimes when frequency is busy it goes down to 2-3Mbps. Clients are mix of Ubnt NS5, NS5Loco, rootena, sxt, rb711 ect. So check your frequency.
Using nv2 on basebox and sxt as clients is whole another story. And it's working just fine and more than fine