We installed a customer yesterday, 5700 SM with reflector and the link efficiency was all good with a good dBm (-68) and a jitter of 2. It’s the best signal that we can get at the customer. They are 2.5 miles away from our tower.
However, we noticed later that the link efficiency changed - the downlink was still the same at 100% whereas the uplink efficiency changes from 95% down to 68% then to 38% then up to 68%. It is currently at about 65%.
The downlink efficiency remains at 100%.
It sounds to me you have very strong interference in the AP side, running the spectrum analyzer in boths sides could help you to choose the best channel to avoid this interference.