I have problem with software OpenWrt in Devices Ubiquiti

I compile many Devices Ubiquiti like
Ubiquiti NanoStation AC loco
Ubiquiti NanoStation Loco M5 xw
Ubiquiti NanoStation M2 xm
Ubiquiti NanoStation M2 xw
Ubiquiti NanoStation M5 xw
Ubiquiti PowerBeam M2-400
Ubiquiti PowerBeam M5-400
everything is fine except frequency M5 there is one problem I have with it
the problem is when I make one device AP(WDS)
and the other ST(WDS) 3 devices connected to AP (WDS) and the 3 device's station (WDS) connected
if one device drop connection or hung up the TX/RX its like
6.0 Mbit/s, 40MHz, MCS 15
270.0 Mbit/s, 40MHz, MCS 14, Short GI
the Signal is good
everything is good I don't know why the device be
6.0 Mbit/s, 40MHz, MCS 15
270.0 Mbit/s, 40MHz, MCS 14, Short GI
from
300 Mbit/s, 40MHz, MCS 15
300 Mbit/s, 40MHz, MCS 15
Suddenly
and the others devices still connected and the signal is good and the TX/RX
like
300.0 Mbit/s, 40MHz, MCS 15, Short GI
270.0 Mbit/s, 40MHz, MCS 15
but the all devices it's hung up and drops connection if I want enter for one of them I can't and the ping dropped until if I disconnect the device
The number one whose signs are
6.0 Mbit/s, 40MHz, MCS 15
270.0 Mbit/s, 40MHz, MCS 14, Short GI
and the other devices still connected and ping of them it's good and i can open them
after a few seconds the device number one it's connected again and working fine

shortly
why if there one device hung up it's dropping ping from other devices until I manually disconnected the device number one

one more thing
why the device number one return from
300.0 Mbit/s, 40MHz, MCS 15, Short GI
270.0 Mbit/s, 40MHz, MCS 15
to
6.0 Mbit/s, 40MHz, MCS 15
270.0 Mbit/s, 40MHz, MCS 14, Short GI
Suddenly
What are the reasons that make it like that
and why the other devices hung up to Even if there connected fine and bandwidth
300.0 Mbit/s, 40MHz, MCS 15, Short GI
270.0 Mbit/s, 40MHz, MCS 15