Uplink problem


I have good RSSI, good Jitter, 0-1% packet loss from both directions (from my switch to the customer SM and from the customer PC to my switch)

I have 1M test file in one of the servers is the switch that customers can download and upload for testing the speed

Recently customer have some problems to upload the file (and of accurse upload attachment to webmails )

The RSSI didn’t changed and jitter is still good, and as I said I do not have any packet loss

I checked the uplink and downlink efficiency and I am usually get 95-100$ efficacy, but from time to time I receive 0 % uplink efficiency (about once in 10 -15 tests – other test are 95-100%) even though I do not loss pings…

I am using 5.4 advantage AP , 5.4 regular SM , software version 8.1.4 , all the AP are synchronized with CMM and GPS ( I use 3 different freq with 25Mhz space)

I tried to disable the 2X operation and its didn’t help
The DFS is diabled in all AP

Please , Any ideas???