Some users report that AR750s has disconnecting problems. We did a lot of test and now you can try firmware 3.029-1120 from GL.iNet download center
It changed the wifi parameters of 2.4G and 5G to make it more compatible. Especially changed
option noscan '0'
option disassoc_low_ack '0'
Please download and upgrade from your existing firmware. If possible do NOT reserve settings to have a clear upgrade.