WLAN 5 GHz band RT-N66U is restarting a few times when i use it much

Hi All,

First, sorry for my bad English.

I have a problem for i while.

When i use the 5 GHz band of my RT-N66U for a moment when copiing or downloading it drops and is not visible for a while. After some time it's back.
I Use Merlin, version 378.56_2

Anybody having the same problem and can it be solved, ?

Log:

Nov 24 11:03:51 dnsmasq-dhcp[246]: DHCPREQUEST(br0)...

WLAN 5 GHz band RT-N66U is restarting a few times when i use it much