We have installed a pair of QRT units as a PTP backhaul, almost 19km, and have very good line of sight. We are using 5GHz-A 20MHz channel with 100% CCQ values and a -61dbm signal on both ends. We can use the built in bandwidth speed test and get good results, usually around 35 mbps to 43mbps using TCP. In actual use we can only push between 3mbps to 6mbps of real data. We have tried N mode, wider and narrower channels, all with no change. Another problem we have is the units will only associate in NV2 protocol. We can't get them to associate using 802.11 or NStreme. I have probably done something wrong but can't figure it out. I have also upgraded to 6.29.1, updated the firmware and have even tried the Wireless-FP package. Any ideas on what might be the problem? I can provide config's if needed.

Check that you don't have duplex mismatch on ethernet interfaces. This is the typical symptom.

I have set all devices to 100Mbps Full Duplex, QRT, Switch and all AP's. It seemed to help a little but I am still not getting much over 6Mbps true Internet throughput. I think I should be getting much more than that. Does anyone know the ideal settings to get Nstreme to work. I have it enabled on both sides of the link but when I change the AP wireless protocol to Nstreme the other side never associates. Is there some setting I have to have to make this work? Shouldn't the CPE follow the AP if the CPE's wireless protocol is set to any? I may not be thinking right on this so any advice would be appreciated. I am currently using 20Mhz wide channel with NV2 protocol.

try this setting on both device (before change to nstreame or 802.11) after try to switch on nstreme or 802.11

I set the security profile to WPA2 and this got the Nstreme & 802.11 protocols working. I have tried using both of those and still can't get any more that 6Mbps of throughput on the link. Are there any other setting that could be limiting this link?