I bought a rb751 few days ago was using it an external antenna 15dbi alfa aoa2412 it was working fine but after a few days the external antenna stopped transmitting I think signals are the client dropped drastically and connectivity went to zero. But now when i enable chain 0 tx within a short range client end gets connectivity and good speed but without chain 0 tx its almost nothing. In scan mode it pick ups a lot of devices with good signals with chain 0 disabled completed connected devices get better signals in wireless registeration but there is no data transfer without chain 0 tx enabled.

was the 751 designed to only last this long ??

I just noticed that my 751 does not give tx ccq for chain 1 or chain 0